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  • Model

    匈牙利算法-DFS

     1 bool dfs(int u){
 2     for(int i = 1; i <= n; i++){
 3         if(a[u][i] && !visit[i]){
 4             visit[i] = true;
 5             if(match[i] == -1 || dfs(match[i])){
 6                 match[i] = u;
 7             }
 8             return true;
 9         }r
10     }
11     return false;
12 }
    View Code

    LCA-RMQ

     1 #include <iostream>
 2 #include <cstdio>
 3 #include <algorithm>
 4 #define LL long long
 5 #define MAXN 10005
 6 #define MAXM 30005
 7 using namespace std;
 8 
 9 int euler[MAXM], deep[MAXM], pos[MAXN];
10 int f[20][MAXN];
11 vector<int>G[MAXN];
12 bool vis[MAXN];
13 int top;
14 int cnt[MAXN];
15 void dfs(int t, int x)
16 {
17     if (pos[x] == -1)
18         pos[x] = top;
19     deep[top] = t;
20     euler[top++] = x;
21 
22     for (int i = 0; i < G[x].size(); i++)
23     {
24         dfs(t + 1, G[x][i]);
25         deep[top] = t;
26         euler[top++] = x;
27     }
28 }
29 
30 void rmq(int n)
31 {
32     for (int i = 1; i <= n; i++)
33         f[0][i] = deep[i];
34     for (int j = 1; j <= (int)(log((double)n) / log(2.0)); j++){
35         for (int i = 1; i <= n - (1 << j) + 1; i++){
36             f[j][i] = min(f[j - 1][i], f[j - 1][i + (1 << (j - 1))]);
37         }
38     }
39 }
40 
41 int get(int x, int y)
42 {
43     if (x > y){
44         swap(x, y);
45     }
46     int k = (int)(log((double)(y - x + 1.0)) / log(2.0));
47     int temp = min(f[k][x], f[k][y - (1 << k) + 1]);
48     for (int i = x; i <= y; i++)
49     if (deep[i] == temp)
50         return euler[i];
51 }
52 
53 int main()
54 {
55     int n;
56     int a, num, b;
57     int root;
58     int m, x, y;
59     int T;
60     scanf("%d", &T);
61     for (int cas = 1; cas <= T; cas++){
62         scanf("%d", &n);
63         top = 1;
64         memset(pos, -1, sizeof(pos));
65         memset(cnt, 0, sizeof(cnt));
66         memset(vis, 0, sizeof(vis));
67         for (int i = 1; i <= n; i++)
68             G[i].clear();
69         for (int i = 1; i < n; i++)
70         {
71             scanf("%d %d", &x, &y);
72             vis[y] = true;
73             G[x].push_back(y);
74         }
75 
76         for (int i = 1; i <= n; i++){
77             if (!vis[i]){
78                 root = i;
79                 break;
80             }
81         }
82         dfs(0, root);
83         rmq(2 * n - 1);
84         scanf("%d %d", &x, &y);
85         printf("%d
", get(pos[x], pos[y]));
86     }
87     return 0;
88 }
    View Code

    MaxFlow - Dinic

     1 struct Edge{
 2     int from, to, cap, flow;
 3     //Edge(int u, int v, int c, int f) :from(u), to(v), cap(c), flow(f){};
 4 };
 5 bool comp(const Edge& a, const Edge& b){
 6     return (a.from < b.from || (a.from == b.from && a.to < b.to));
 7 }
 8 struct Dinic{
 9     int n, m, i, s, t;
10     Edge e;
11     vector<Edge> edges;
12     vector<int> G[MAXN];
13     int d[MAXN], cur[MAXN];
14     bool vis[MAXN];
15     void init(int n){
16         this->n = n;
17         for (i = 0; i <= n; i++){
18             G[i].clear();
19         }
20         edges.clear();
21     }
22     void AddEdge(int from, int to, int cap){
23         edges.push_back(Edge{ from, to, cap, 0 });
24         edges.push_back(Edge{ to, from, 0, 0 });
25         m = edges.size();
26         G[from].push_back(m - 2);
27         G[to].push_back(m - 1);
28     }
29     bool BFS(){
30         memset(vis, 0, sizeof(vis));
31         queue<int> Q;
32         Q.push(s);
33         d[s] = 0;
34         vis[s] = 1;
35         while (!Q.empty()){
36             int x = Q.front();
37             Q.pop();
38             for (i = 0; i < G[x].size(); i++){
39                 Edge& e = edges[G[x][i]];
40                 if (!vis[e.to] && e.cap > e.flow){
41                     vis[e.to] = true;
42                     d[e.to] = d[x] + 1;
43                     Q.push(e.to);
44                 }
45             }
46         }
47         return vis[t];
48     }
49     int DFS(int x, int a){
50         if (x == t || a == 0) return a;
51         int flow = 0, f;
52         for (int& i = cur[x]; i < G[x].size(); i++){
53             Edge& e = edges[G[x][i]];
54             if (d[x] + 1 == d[e.to] && (f = DFS(e.to, min(a, e.cap - e.flow))) > 0){
55                 e.flow += f;
56                 edges[G[x][i] ^ 1].flow -= f;
57                 flow += f;
58                 a -= f;
59                 if (a == 0) break;
60             }
61         }
62         return flow;
63     }
64     int MaxFlow(int s, int t, int need){
65         int flow = 0;
66         this->s = s;
67         this->t = t;
68         while (BFS()){
69             memset(cur, 0, sizeof(cur));
70             flow += DFS(s, INF);
71             if (flow > need) return flow;
72         }
73         return flow;
74     }
75     bool checkFull(int s){
76         for (int i = 0; i < G[s].size(); i++){
77             if (edges[G[s][i]].flow != edges[G[s][i]].cap){
78                 return false;
79             }
80         }
81         return  true;
82     }
83 };
    View Code

    MCMF

     1 #include <iostream>
 2 #include <string.h>
 3 #include <stdio.h>
 4 #include <algorithm>
 5 #include <queue>
 6 #define V 10100
 7 #define E 1000100
 8 #define inf 99999999
 9 using namespace std;
10 int vis[V];
11 int dist[V];
12 int pre[V];
13 
14 struct Edge{
15     int u,v,c,cost,next;
16 }edge[E];
17 int head[V],cnt;
18 
19 void init(){
20     cnt=0;
21     memset(head,-1,sizeof(head));
22 }
23 void addedge(int u,int v,int c,int cost)
24 {
25     edge[cnt].u=u;edge[cnt].v=v;edge[cnt].cost=cost;
26     edge[cnt].c=c;edge[cnt].next=head[u];head[u]=cnt++;
27 
28     edge[cnt].u=v;edge[cnt].v=u;edge[cnt].cost=-cost;
29     edge[cnt].c=0;edge[cnt].next=head[v];head[v]=cnt++;
30 }
31 
32 bool spfa(int begin,int end){
33     int u,v;
34     queue<int> q;
35     for(int i=0;i<=end+2;i++){
36         pre[i]=-1;
37         vis[i]=0;
38         dist[i]=inf;
39     }
40     vis[begin]=1;
41     dist[begin]=0;
42     q.push(begin);
43     while(!q.empty()){
44         u=q.front();
45         q.pop();
46         vis[u]=0;
47         for(int i=head[u];i!=-1;i=edge[i].next){
48             if(edge[i].c>0){
49                 v=edge[i].v;
50                 if(dist[v]>dist[u]+edge[i].cost){
51                     dist[v]=dist[u]+edge[i].cost;
52                     pre[v]=i;
53                     if(!vis[v]){
54                         vis[v]=true;
55                         q.push(v);
56                     }
57                 }
58             }
59         }
60     }
61     return dist[end]!=inf;
62 }
63 
64 int MCMF(int begin,int end){
65     int ans=0,flow;
66     int flow_sum=0;
67     while(spfa(begin,end)){
68         flow=inf;
69         for(int i=pre[end];i!=-1;i=pre[edge[i].u])
70             if(edge[i].c<flow)
71                 flow=edge[i].c;
72         for(int i=pre[end];i!=-1;i=pre[edge[i].u]){
73             edge[i].c-=flow;
74             edge[i^1].c+=flow;
75         }
76         ans+=dist[end];
77         flow_sum += flow;
78     }
79     //cout << flow_sum << endl;
80     return ans;
81 }
82 
83 int main()
84 {
85     //freopen("in.txt","r",stdin);
86     int n,m,a,b,c;
87     while(scanf("%d%d",&n,&m)!=EOF){
88         init();
89         addedge(0,1,2,0);
90         addedge(n,n+1,2,0);
91         for(int i=1;i<=m;i++){
92             scanf("%d%d%d",&a,&b,&c);
93             addedge(a,b,1,c);
94             addedge(b,a,1,c);
95         }
96         printf("%d
",MCMF(0,n+1));
97     }
98     return 0;
99 }
    View Code

    RMQ - ST

     1 void rmq(int n)
 2 {
 3     for (int i = 1; i <= n; i++)
 4         f[0][i] = deep[i];
 5     for (int j = 1; j <= (int)(log((double)n) / log(2.0)); j++){
 6         for (int i = 1; i <= n - (1 << j) + 1; i++){
 7             f[j][i] = min(f[j - 1][i], f[j - 1][i + (1 << (j - 1))]);
 8         }
 9     }
10 }
    View Code

    Two-SAT

     1 struct TwoSat{
 2     int n;
 3     vector<int> G[MAXN*2];
 4     bool mark[MAXN*2];
 5     int S[MAXN*2], c;
 6 
 7     bool dfs(int x){
 8         if(mark[x^1]) return false;
 9         if(mark[x]) return true;
10         mark[x] = true;
11         S[c++] = x;
12         for(int i = 0; i < G[x].size(); i++){
13             if(!dfs(G[x][i])) return false;
14         }
15         return true;
16     }
17 
18     void init(int n){
19         this->n = n;
20         for(int i = 0; i < n * 2; i++){
21             G[i].clear();
22         }
23         memset(mark, 0, sizeof(mark));
24     }
25 
26     void add_clause(int x, int xval, int y, int yval){
27         x = x * 2 + xval;
28         y = y * 2 + yval;
29         G[x^1].push_back(y);
30         G[y^1].push_back(x);
31     }
32 
33     bool solve(){
34         for(int i = 0; i < n * 2; i += 2){
35             if(!mark[i] && !mark[i + 1]){
36                 c = 0;
37                 if(!dfs(i)){
38                     while(c > 0){
39                         mark[S[--c]] = false;
40                     }
41                     if(!dfs(i + 1)){
42                         return false;
43                     }
44                 }
45             }
46         }
47         return true;
48     }
49 };
    View Code

    计算几何

     1 #define eps 1e-8
 2 int dcmp(double x){
 3     if (fabs(x) < eps) return 0;
 4     return x < 0 ? -1 : 1;
 5 }
 6 struct Point{
 7     double x, y;
 8     Point(double p = 0, double q = 0){
 9         x = p;
10         y = q;
11     }
12 };
13 struct Node{
14     int p;
15     Point a, b;
16     Node(Point a1, Point a2, int t){
17         a = a1;
18         b = a2;
19         p = t;
20     }
21 };
22 
23 typedef Point Vector;
24 
25 Vector operator + (Vector A, Vector B){
26     return Vector(A.x + B.x, A.y + B.y);
27 }
28 Vector operator - (Vector A, Vector B){
29     return Vector(A.x - B.x, A.y - B.y);
30 }
31 Vector operator * (Vector A, double p){
32     return Vector(A.x * p, A.y * p);
33 }
34 Vector operator / (Vector A, double p){
35     return Vector(A.x / p, A.y / p);
36 }
37 bool operator == (Vector A, Vector B){
38     return dcmp(A.x - B.x) == 0 && dcmp(A.y - B.y) == 0;
39 }
40 bool operator > (Vector A, Vector B){
41     return A.x > B.x && A.y > B.y;
42 }
43 bool operator <(Vector A, Vector B){
44     return A.x < B.x && A.y < B.y;
45 }
46 //点积
47 double  Dot(Vector A, Vector B){
48     return A.x * B.x + A.y * B.y;
49 }
50 //模
51 double Length(Vector A){
52     return sqrt(Dot(A, A));
53 }
54 //夹角
55 double Angle(Vector A, Vector B){
56     return acos(Dot(A, B) / Length(A) / Length(B));
57 }
58 //叉积
59 double Cross(Vector A, Vector B){
60     return A.x * B.y - A.y*B.x;
61 }
62 //三角形面积
63 double Area2(Point A, Point B, Point C){
64     return Cross(B - A, C - A);
65 }
66 //点在直线上投影
67 Point GetLineProjection(Point P, Point A, Point B){
68     Vector v = B - A;
69     return A + v * (Dot(v, P - A) / Dot(v, v));
70 }
71 //线段相交(不含端点)
72 bool SegmentProperIntersection(Point a1, Point a2, Point b1, Point b2){
73     double c1 = Cross(a2 - a1, b1 - a1);
74     double c2 = Cross(a2 - a1, b2 - a1);
75     double c3 = Cross(b2 - b1, a1 - b1);
76     double c4 = Cross(b2 - b1, a2 - b1);
77     return dcmp(c1) * dcmp(c2) < 0 && dcmp(c3) * dcmp(c4) < 0;
78 }
79 //点在直线上(不含端点)
80 bool OnSegment(Point p, Point a1, Point a2){
81     return dcmp(Cross(a1 - p, a2 - p)) == 0 && dcmp(Dot(a1 - p, a2 - p)) < 0;
82 }
    View Code

    KMP

     1 int n, last[MAXN], j, m = 0;
 2 char s[MAXN];
 3 int main()
 4 {
 5     while (~scanf("%d", &n)){
 6         if (n == 0) break;
 7         memset(last, 0, sizeof(last));
 8         scanf("%s", s + 1);
 9 
10         int k = 0;
11         last[1] = 0;
12         for (int i = 2; i <= n; i++){
13             while (s[k + 1] != s[i] && k > 0){
14                 k = last[k];
15             }
16             if (s[k + 1] == s[i]){
17                 k++;
18             }
19             last[i] = k;
20         }
21         printf("Test case #%d
", ++m);
22         for (int i = 2; i <= n; i++){
23             j = i - last[i];
24             if (i % j == 0 && i > j){
25                 printf("%d %d
", i, i / j);
26             }
27         }
28         printf("
");
29     }
30 }
    View Code

    AC自动机

      1 int cnt[200];
  2 char s[MAXM];
  3 char words[160][100];
  4 int n, ans;
  5 
  6 struct Node
  7 {
  8     int count, id;
  9     struct Node *next[26];
 10     struct Node *fail;
 11     void init(){
 12         int i;
 13         for (int i = 0; i < 26; i++){
 14             next[i] = NULL;
 15         }
 16         count = -1;
 17         fail = NULL;
 18         id = -1;
 19     }
 20 };
 21 Node *root, *d[MAXM];
 22 
 23 
 24 void insert(char *s, int id){
 25     int len, k;
 26     Node *p = root;
 27     len = strlen(s);
 28     for (k = 0; k < len; k++){
 29         int pos = s[k] - 'a';
 30         if (p->next[pos] == NULL){
 31             p->next[pos] = new Node;
 32             p->next[pos]->init();
 33             p = p->next[pos];
 34         }
 35         else
 36             p = p->next[pos];
 37     }
 38     p->count = id;
 39 }
 40 
 41 void build(Node *root){
 42     int head, tail, i;
 43     Node *p, *temp;
 44     head = 0;
 45     tail = 0;
 46     root->fail = NULL;
 47     d[head] = root;
 48     while (head <= tail){
 49         temp = d[head++];
 50         for (int i = 0; i < 26; i++){
 51             if (temp->next[i] == NULL) continue;
 52             if (temp == root){
 53                 temp->next[i]->fail = root;
 54             }
 55             else{
 56                 p = temp->fail;
 57                 while (p != NULL){
 58                     if (p->next[i] != NULL){
 59                         temp->next[i]->fail = p->next[i];
 60                         break;
 61                     }
 62                     p = p->fail;
 63                 }
 64                 if (p == NULL){
 65                     temp->next[i]->fail = root;
 66                 }
 67             }
 68             d[++tail] = temp->next[i];
 69         }
 70     }
 71 }
 72 
 73 void query(){
 74     int len = strlen(s);
 75     Node *p, *temp;
 76     p = root;
 77     for (int i = 0; i < len; i++){
 78         int pos = s[i] - 'a';
 79         while (!p->next[pos] && p != root)  p = p->fail;
 80         p = p->next[pos];
 81         if (!p) p = root;
 82         temp = p;
 83         while (temp != root){
 84             if (temp->count >= 0){
 85                 cnt[temp->count]++;
 86             }
 87             temp = temp->fail;
 88         }
 89     }
 90 }
 91 
 92 
 93 int main()
 94 {
 95     while (~scanf("%d", &n)){
 96         if (n == 0) break;
 97         memset(cnt, 0, sizeof(cnt));
 98         root = new Node;
 99         root->init();
100         for (int i = 0; i < n; i++){
101             scanf("%s", &words[i]);
102             insert(words[i], i);
103         }
104         build(root);
105         scanf("%s", s);
106         query();
107         ans = -1;
108         for (int i = 0; i < n; i++){
109             if (cnt[i] >ans){
110                 ans = cnt[i];
111             }
112         }
113         printf("%d
", ans);
114         for (int i = 0; i < n; i++){
115             if (cnt[i] == ans){
116                 printf("%s
", words[i]);
117             }
118         }
119     }
120 }
    View Code

    后缀数组

     1 char str[MAXN];
 2 int m, dn;
 3 int s[MAXN], sa[MAXN], height[MAXN], p[MAXN], q[MAXN], c[MAXN];
 4 int ranK[MAXN];
 5 int f[MAXN * 2][45];
 6 
 7 void getSa(){
 8     for (int i = 0; i < dn; i++){
 9         p[i] = s[i];
10         c[s[i]]++;
11     }
12     for (int i = 1; i < m; i++){
13         c[i] += c[i - 1];
14     }
15     for (int i = dn - 1; i >= 0; i--){
16         sa[--c[p[i]]] = i;
17     }
18     for (int k = 1; k <= dn; k *= 2){
19         int t = 0;
20         for (int i = dn - k; i < dn; i++){
21             q[t++] = i;
22         }
23         for (int i = 0; i < dn; i++){
24             if (sa[i] >= k){
25                 q[t++] = sa[i] - k;
26             }
27         }
28         for (int i = 0; i < m; i++){
29             c[i] = 0;
30         }
31         for (int i = 0; i < dn; i++){
32             c[p[q[i]]]++;
33         }
34         for (int i = 0; i < m; i++){
35             c[i] += c[i - 1];
36         }
37         for (int i = dn - 1; i >= 0; i--){
38             sa[--c[p[q[i]]]] = q[i];
39         }
40 
41         swap(p, q);
42         t = 1;
43         p[sa[0]] = 0;
44         for (int i = 1; i < dn; i++){
45             if (q[sa[i - 1]] == q[sa[i]] && q[sa[i - 1] + k] == q[sa[i] + k]){
46                 p[sa[i]] = t - 1;
47             }
48             else{
49                 p[sa[i]] = t++;
50             }
51         }
52         if (t >= dn) break;
53         m = t;
54     }
55 
56 }
57 
58 void getHeight(){
59     for (int i = 0; i < dn; i++){
60         ranK[sa[i]] = i;
61     }
62     int k = 0;
63     for (int i = 0; i < dn; i++){
64         if (k != 0) k--;
65         int j = sa[ranK[i] - 1];
66         while (s[i + k] == s[j + k]){
67             k++;
68         }
69         height[ranK[i]] = k;
70     }
71 }
    View Code

    Manacher算法

     1 char s[MAXN << 1], ss[MAXN];
 2 int p[MAXN << 1];
 3 
 4 int manacher(int m){
 5     s[0] = '@';
 6     s[1] = '#';
 7     for (int i = 1, j = 2; i <= m; i++, j += 2){
 8         s[j] = ss[i];
 9         s[j + 1] = '#';
10     }
11     m = (m << 1) + 1;
12     int res = 0, id = 0;
13     int ans = 0;
14     for (int i = 1; i <= m; i++) {
15         if (res > i){
16             p[i] = min(p[2 * id - i], res - i);
17         }
18         else{
19             p[i] = 1;
20         }
21         while (s[i + p[i]] == s[i - p[i]]){
22             p[i]++;
23         }
24         if (i + p[i] > res) {
25             res = i + p[i];
26             id = i;
27         }
28         ans = max(p[i], ans);
29     }
30     return ans - 1;
31 }
    View Code

     字符串最小表示

     1 int min_max_express(char s[], int m, bool flag){
 2     //s从0开始, flag=true时最小表示
 3     int i = 0, j = 1, k = 0;
 4     while (i < m && j < m && k < m){
 5         int p = s[(j + k) % m] - s[(i + k) % m];
 6         if (p == 0){
 7             k++;
 8         }
 9         else{
10             if (flag){
11                 if (p > 0){
12                     j += k + 1;
13                 }
14                 else{
15                     i += k + 1;
16                 }
17             }
18             else{
19                 if (p > 0){
20                     i += k + 1;
21                 }
22                 else{
23                     j += k + 1;
24                 }
25             }
26             if (i == j){
27                 j++;
28             }
29             k = 0;
30         }
31     }
32     return min(i, j);
33 }
    View Code

    Dijstra

     1 struct Edge
 2 {
 3     int from, to, dist;
 4     Edge(int from, int to, int dist):from(from), to(to), dist(dist){};
 5 };
 6 struct HeapNode
 7 {
 8     int d, u;
 9     HeapNode(int d, int u):d(d), u(u){};
10     bool operator <(const HeapNode& rhs) const{
11         return d > rhs.d;
12     }
13 };
14 struct Dijstra
15 {
16     int n, m;
17     vector<Edge> edges;
18     vector<int> G[MAXN];
19     bool done[MAXN];
20     int d[MAXN];
21     int p[MAXN];
22 
23     void init(int n){
24         this->n = n;
25         for(int i = 0; i <= n; i++){
26             G[i].clear();
27             road[i].clear();
28         }
29         edges.clear();
30     }
31 
32     void AddEdge(int from, int to, int dist){
33         edges.push_back(Edge(from, to, dist));
34         m = edges.size();
35         G[from].push_back(m - 1);
36     }
37 
38     void dijstra(int s){
39         priority_queue<HeapNode> Q;
40         for(int i = 0; i <= n; i++){
41             d[i] = INF;
42         }
43         d[s] = 0;
44         memset(done, 0, sizeof(done));
45         Q.push(HeapNode(0, s));
46         while(!Q.empty()){
47             HeapNode x = Q.top();
48             Q.pop();
49             int u = x.u;
50             if(done[u]) continue;
51             done[u]  = true;
52             for(int i = 0; i < G[u].size(); i++){
53                 Edge& e = edges[G[u][i]];
54                 if(d[e.to] > d[u] + e.dist){
55                     d[e.to] = d[u] + e.dist;
56                     p[e.to] = G[u][i];
57                     Q.push(HeapNode(d[e.to], e.to));
58                 }
59             }
60         }
61     }
62 };
    View Code

    Prim

     1 int  prim() {
 2     memset(vis,0,sizeof(vis));
 3     int i;
 4     int  maxedge=0;
 5     for (i = 1; i <= n; i++) {
 6         dis[i]= value[1][i];
 7     }
 8     dis[1] = 0;
 9     vis[1] = true;
10     for (i = 2; i <= n; i++) {
11         int temp = inf;
12         int mark;
13         for (int j = 1; j <= n; j++) {
14             if (!vis[j] && dis[j] < temp) {
15                 temp = dis[j];
16                 mark = j;
17             }
18         }
19         if(dis[mark]>maxedge)
20             maxedge=dis[mark];
21         vis[mark]=true;
22         for (int j = 1; j <= n; j++) {
23             if (!vis[j]&&dis[j]>value[mark][j])
24                 dis[j] = value[mark][j];
25         }
26     }
27     return maxedge;
28 }
    View Code

    Spfa

     1 int spfa(int s)
 2 {
 3     queue <int> q;
 4     memset(d, INF, sizeof(d));
 5     d[s] = 0;
 6     memset(cnt, 0, sizeof(cnt));
 7     memset(vis, 0, sizeof(vis));
 8     q.push(s);
 9     vis[s] = 1;
10     while (!q.empty())
11     {
12         int x;
13         x = q.front(); 
14         q.pop();  
15         while (no[x]){
16             x = q.front();
17             q.pop();
18         }
19         vis[x] = 0;
20         for (int i = 0; i < G[x].size(); i++)
21         {
22             int y = G[x][i].v;
23             if (d[x] + G[x][i].w < d[y])
24             {
25                 d[y] = d[x] + G[x][i].w;
26                 if (!vis[y])
27                 {
28                     vis[y] = 1;
29                         q.push(y);
30                 }
31             }
32         }
33     }
34 }
    View Code

    有向图 强连通分量Tarjan

     1 int pre[MAXN], lowlink[MAXN], sccno[MAXN];
 2 vector<int> G[MAXN];
 3 stack<int> S;
 4 int dfs_clock, scc_cnt;
 5 void dfs(int u){
 6     pre[u] = lowlink[u] = ++dfs_clock;
 7     S.push(u);
 8     for (int i = 0; i < G[u].size(); i++){
 9         int v = G[u][i];
10         if (!pre[v]){
11             dfs(v);
12             lowlink[u] = min(lowlink[u], lowlink[v]);
13         }
14         else{
15             if (!sccno[v]){
16                 lowlink[u] = min(lowlink[u], pre[v]);
17             }
18         }
19     }
20     if (lowlink[u] == pre[u]){
21         scc_cnt++;
22         for (;;){
23             int x = S.top();
24             S.pop();
25             sccno[x] = scc_cnt;
26             if (x == u) break;
27         }
28     }
29 }
30 void find_scc(int n){
31     dfs_clock = scc_cnt = 0;
32     memset(sccno, 0, sizeof(sccno));
33     memset(pre, 0, sizeof(pre));
34     for (int i = 1; i <= n; i++){
35         if (!pre[i]){
36             dfs(i);
37         }
38     }
39 }
    View Code

    无向图 点-双连通分量

     1 struct Edge{
 2     int from, to;
 3     Edge(int from = 0, int to = 0) :from(from), to(to){};
 4 };
 5 vector<int> G[MAXN], bcc[MAXN];
 6 int pre[MAXN], iscut[MAXN], bccno[MAXN], pre[MAXN];
 7 stack<Edge> S;
 8 int dfs_clock, bcc_cnt, bridge_cnt;
 9 int dfs(int u, int fa)
10 {
11     int lowu = pre[u] = ++dfs_clock;
12     int child = 0;
13     for (int i = 0; i < G[u].size(); i++){
14         int v = G[u][i];
15         Edge e = Edge(u, v);
16         if (!pre[v]){
17             S.push(e);
18             child++;
19             int lowv = dfs(v, u);
20             lowu = min(lowu, lowv);
21             if (lowv >= pre[u]){
22                 iscut[u] = true;
23                 bcc_cnt++;
24                 bcc[bcc_cnt].clear();
25                 while (true){
26                     Edge x = S.top(); S.pop();
27                     if (bccno[x.from] != bcc_cnt){ 
28                         bcc[bcc_cnt].push_back(x.from);
29                         bccno[x.from] = bcc_cnt;
30                     }
31                     if (bccno[x.to] != bcc_cnt){
32                         bcc[bcc_cnt].push_back(x.to);
33                         bccno[x.to] = bcc_cnt;
34                     }
35                     if (x.from == u && x.to == v) break;
36                 }
37             }
38         }
39         else if (pre[v] < pre[u] && v != fa){
40             S.push(e);
41             lowu = min(lowu, pre[v]);
42         }
43     }
44     if (fa < 0 && child == 1) iscut[u] = false;
45     return lowu;
46 }
47 void find_bcc(int n)
48 {
49     memset(pre, 0, sizeof(pre));
50     memset(iscut, 0, sizeof(iscut));
51     memset(bccno, 0, sizeof(bccno));
52     dfs_clock = bcc_cnt = 0;
53     bridge_cnt = 0;
54     for (int i = 0; i < n; i++){
55         if (!pre[i]) dfs(i, -1);
56     }
57 }
    View Code

    无向图 边-双连通分量

     1 struct Edge{
 2     int v, next;
 3 }edge[MAXN * 4];
 4 
 5 int n, m, cnt, NE, bridge_cnt;
 6 int head[MAXN];
 7 int parent[MAXN];
 8 int isbridge[MAXN], low[MAXN], pre[MAXN];
 9 bool mark[MAXN];
10 
11 void add_edge(int u, int v){
12     edge[NE].v = v;
13     edge[NE].next = head[u];
14     head[u] = NE++;
15 }
16 
17 void dfs(int u, int father){
18     int flag = 0;
19     low[u] = pre[u] = ++cnt;
20     mark[u] = true;
21     for (int i = head[u]; i != -1; i = edge[i].next){
22         int v = edge[i].v;
23         if (v == father&&!flag){ flag = 1; continue; }
24         if (pre[v] == 0){
25             parent[v] = u;
26             dfs(v, u);
27             low[u] = min(low[u], low[v]);
28             if (low[v] > pre[u]){
29                 isbridge[v] = 1;
30                 bridge_cnt++;
31             }
32         }
33         else if (mark[v]){
34             low[u] = min(low[u], pre[v]);
35         }
36     }
37 }
38 void find_bcc(){
39     memset(isbridge, 0, sizeof(isbridge));
40     memset(pre, 0, sizeof(pre));
41     memset(mark, false, sizeof(mark));
42     for (int i = 1; i <= n; i++){
43         if (!pre[i])dfs(1, -1);
44     }
45 }
    View Code

    无向图 全局最小割 Stoer Wagner

     1 int a[MAXN][MAXN], v[MAXN], dis[MAXN];
 2 bool vis[MAXN];
 3 int stoer_wagner(int n){
 4     int res = INF;
 5     for (int i = 0; i < n; i++){
 6         v[i] = i + 1;
 7     }
 8     while (n > 1){
 9         int maxp = 1, pre = 0;
10         for (int i = 1; i < n; i++){
11             dis[v[i]] = a[v[0]][v[i]];
12             if (dis[v[i]] > dis[v[maxp]]){
13                 maxp = i;
14             }
15         }
16         memset(vis, 0, sizeof(vis));
17         vis[v[0]] = true;
18         for (int i = 1; i < n; i++){
19             if (i == n - 1){
20                 res = min(res, dis[v[maxp]]);
21                 for (int j = 0; j < n; j++){
22                     a[v[pre]][v[j]] += a[v[j]][v[maxp]];
23                     a[v[j]][v[pre]] = a[v[pre]][v[j]];
24                 }
25                 v[maxp] = v[--n];
26             }
27             vis[v[maxp]] = true;
28             pre = maxp;
29             maxp = -1;
30             for (int j = 1; j < n; j++){
31                 if (!vis[v[j]]){
32                     dis[v[j]] += a[v[pre]][v[j]];
33                     if (maxp == -1 || dis[v[maxp]] < dis[v[j]]){
34                         maxp = j;
35                     }
36                 }
37             }
38         }
39     }
40     return res;
41 }
    View Code

    树状数组

     1 int lowbit(int x)
 2 {
 3     return x & (-x);
 4 }
 5 void modify(int x,int add)//一维
 6 {  
 7     while(x<=MAXN)  
 8     {      
 9         a[x]+=add;    
10         x+=lowbit(x); 
11     }
12 }
13 int get_sum(int x)
14 {  
15     int ret=0; 
16     while(x!=0)  
17     {       
18         ret+=a[x];   
19         x-=lowbit(x);   
20     }  
21     return ret;
22 }
23 void modify(int x,int y,int data)//二维
24 {
25     for(int i=x;i<MAXN;i+=lowbit(i))
26         for(int j=y;j<MAXN;j+=lowbit(j))
27             a[i][j]+=data;
28 }
29 int get_sum(int x,int y)
30 {
31     int res=0;
32     for(int i=x;i>0;i-=lowbit(i))
33         for(int j=y;j>0;j-=lowbit(j))
34             res+=a[i][j];
35     return res;
36 }
    View Code

    Tarjan

     1 int pre[MAXN], isbridge[MAXM], low[MAXN];
 2 vector<Edge> G[MAXN];
 3 int dfs_clock;
 4 int dfs(int u, int father){
 5     int lowu = pre[u] = ++dfs_clock;
 6     //int child = 0;
 7     for (int i = 0; i < G[u].size(); i++){
 8         int v = G[u][i].to;
 9         if (!pre[v]){
10             //child++;
11             int lowv = dfs(v, G[u][i].pos);
12             lowu = min(lowu, lowv);
13             if (lowv > pre[u]){
14                 isbridge[G[u][i].pos] = true;
15             }
16         }
17         else if (pre[v] < pre[u] && G[u][i].pos != father){
18             lowu = min(lowu, pre[v]);
19         }
20     }
21     low[u] = lowu;
22     return lowu;
23 }
    View Code

    线段树

     1 int sum[MAXN * 3], add[MAXN * 3];
 2 void pushup(int t){
 3     sum[t] = sum[t << 1] + sum[t << 1 | 1];
 4 }
 5 void pushdown(int t, int x){
 6     if (add[t]){
 7         add[t << 1] += add[t];
 8         add[t << 1 | 1] += add[t];
 9         sum[t << 1] += ((x + 1) >> 1)* add[t];
10         sum[t << 1 | 1] += (x >> 1) * add[t];
11         add[t] = 0;
12     }
13 }
14 void update(int L, int R, int t, int p, int q, int x){
15     if (p <= L && q >= R){
16         sum[t] += (R - L + 1) * x;
17         add[t] += x;
18         return;
19     }
20 
21     pushdown(t, R - L + 1);
22     int mid = (L + R) >> 1;
23     if (p <= mid){
24         update(L, mid, t << 1, p, q, x);
25     }
26     if (q > mid){
27         update(mid + 1, R, t << 1 | 1, p, q, x);
28     }
29     pushup(t);
30 }
31 int query(int L, int R, int t, int p, int q){
32     if (p <= L && q >= R){
33         return sum[t];
34     }
35     pushdown(t, R - L + 1);
36     int mid = (L + R) >> 1;
37     int res = 0;
38     if (p <= mid)
39         res += query(L, mid, t << 1, p, q);
40     }
41     if (q > mid){
42         res += query(mid + 1, R, t << 1 | 1, p, q);
43     }
44     return  res;
45 }
46 void build(int L, int R, int t){
47     if (L == R){
48         sum[t] = 1;
49         return;
50     }
51     int mid = (L + R) >> 1;
52     build(L, mid, t << 1);
53     build(mid + 1, R, t << 1 | 1);
54     sum[t] = sum[t << 1] + sum[t << 1 | 1];
55 }
    View Code

    二叉查找树

     1 struct Node{
 2     int x;
 3     Node *left, *right;
 4     Node(int x = 0) :x(x){
 5         left = NULL;
 6         right = NULL;
 7     }
 8 };
 9 Node *root;
10 int bst_insert(int x){
11     if (root == NULL){
12         root = new Node(x);
13         return 1;
14     }
15     Node *p = root;
16     int t = 1;
17     while (p != NULL){
18         if (x > p->x){
19             t = t << 1 | 1;
20             if (p->right == NULL){
21                 p->right = new Node(x);
22                 break;
23             }
24             else{
25                 p = p->right;
26             }
27         }
28         else{
29             t = t << 1;
30             if (p->left == NULL){
31                 p->left = new Node(x);
32                 break;
33             }
34             else{
35                 p = p->left;
36             }
37         }
38     }
39     return t;
40 }
    View Code

     词法分析器

      1 /*======================================================
  2 #
  3 # author: macan
  4 #
  5 # email: macinchang@gmail.com
  6 #
  7 # created time 2015-10-22 18:42:13
  8 #
  9 # last modified: 2015-10-22 18:42
 10 #
 11 # filename: main.cpp
 12 #
 13 =====================================================*/
 14 #include <bits/stdc++.h>
 15 using namespace std;
 16 #define OPEN_FILE
 17 #define MAXN 101
 18 #define INF 0x3f3f3f3f
 19 bool express();
 20 
 21 struct Word{
 22     int syn, integer, decimal, _index;
 23     char *v;
 24     //Word(){};
 25     Word(int syn = 0, int integer = 0, int decimal = 0, int  _index = 0, char *v = NULL):syn(syn), integer(integer), decimal(decimal), _index(_index), v(v){};
 26 };
 27 vector<Word> words;
 28 char *keyword[10]= {"main", "begin", "int", "float", "double", "char", "if", "else", "do", "while"};
 29 char token[MAXN];
 30 vector<char> buf;
 31 int integer, decimal, _index, cnt;
 32 int syn, last, pos, len;
 33 bool wrong;
 34 
 35 void read() {
 36     char ch;
 37     buf.clear();
 38     while(~scanf("%c", &ch)){
 39         buf.push_back(ch);
 40         if(ch == '#') break;
 41     }
 42     len = buf.size();
 43     if(buf[len - 1] != '#'){
 44         buf.push_back('#');
 45         len++;
 46     }
 47 }
 48 
 49 void error(){
 50     printf("Whoops! Looks like something went wrong...
");
 51     wrong = true;
 52 }
 53 
 54 int iskeyword(char *s){
 55     for(int i = 0; i < 10; i++){
 56         if(strcmp(s, keyword[i]) == 0){
 57             return i + 1;
 58         }
 59     }
 60     return 0;
 61 }
 62 
 63 bool isnumber(char ch){
 64     return ch >= '0' && ch <= '9';
 65 }
 66 
 67 void init(){
 68     last = syn;
 69     integer = decimal = _index = 0;
 70     memset(token, 0, sizeof(token));
 71     cnt = 0;
 72 }
 73 
 74 int scaner(){
 75     int flag = 0;
 76     char ch = buf[pos++];
 77     while(ch == ' ' || ch == '
' || ch == '	'){
 78         if(pos >= len) return 0;
 79         ch = buf[pos++];
 80     }
 81     while(ch != 0){
 82         if(flag == 0) init();
 83         if(isalpha(ch) != 0){
 84             token[cnt++] = ch;
 85             ch = buf[pos++];
 86             while(isalnum(ch)){
 87                 token[cnt++] = ch;
 88                 ch = buf[pos++];
 89             }
 90             syn = iskeyword(token);
 91             if(syn == 0){
 92                 syn = 10;
 93             }
 94             pos--;
 95             return syn;
 96         }
 97         if(isnumber(ch)){
 98             integer = decimal = _index = 0;
 99             integer = ch - '0';
100             token[cnt++] = ch;
101             ch = buf[pos++];
102             while(isnumber(ch)){
103                 integer = integer * 10 + (ch - '0');
104                 token[cnt++] = ch;
105                 ch = buf[pos++];
106             }
107             if(flag)    integer *= flag;
108             if(ch == '.'){
109                 token[cnt++] = ch;
110                 ch = buf[pos++];
111                 if(!isnumber(ch)) return -1;
112                 decimal = 0;
113                 while(isnumber(ch)){
114                     decimal = decimal * 10 + (ch - '0');
115                     token[cnt++] = ch;
116                     ch = buf[pos++];
117                 }
118             }
119             if(flag)    decimal *= flag;
120             if(ch == 'e'){
121                 int p = 1;
122                 token[cnt++] = ch;
123                 ch = buf[pos++];
124                 if(ch == '+' || ch == '-'){
125                     token[cnt++] = ch;
126                     p = ch == '-' ? -1 : 1;
127                     ch = buf[pos++];
128                 }
129                 if(!isnumber(ch)) return -1;
130                 _index = 0;
131                 while(isnumber(ch)){
132                     _index = _index * 10 + (ch - '0');
133                     token[cnt++] = ch;
134                     ch = buf[pos++];
135                 }
136                 _index *= p;
137             }
138             syn = 20;
139             flag = true;
140             //print(syn, token);
141             pos--;
142             return syn;
143         }
144 
145         if(ch == '+' || ch == '-'){
146             token[cnt++] = ch;
147             syn = ch == '+' ? 22 : 23;
148             ch = buf[pos];
149             if(last != 20 && last != 10 && isnumber(ch)){
150                 flag = syn == 22 ? 1 : -1;
151                 pos++;
152                 continue;
153             }
154            // print(syn, token);
155             return syn;
156         }
157         if(ch == '<'){
158             token[cnt++] = ch;
159             ch = buf[pos++];
160             if(ch == '='){
161                 token[cnt++] = ch;
162                 syn = 35;
163             }else{
164                 pos--;
165                 syn = 34;
166             }
167             //print(syn, token);
168             return syn;
169         }
170         if(ch == '>'){
171             token[cnt++] = ch;
172             ch = buf[pos++];
173             if(ch == '='){
174                 token[cnt++] = ch;
175                 syn = 33;
176             }else{
177                 pos--;
178                 syn = 32;
179             }
180             //print(syn, token);
181             return syn;
182         }
183         if(ch == '='){
184             token[cnt++] = ch;
185             ch = buf[pos++];
186             if(ch == '='){
187                 token[cnt++] = ch;
188                 syn = 36;
189             }else{
190                 pos--;
191                 syn = 21;
192             }
193             //print(syn, token);
194             return syn;
195         }
196         bool is_comment = false;
197         switch(ch){
198             case '*':
199                 syn = 24;
200                 break;
201             case '/':
202                 if(buf[pos] == '/'){
203                     //ÐÐ×¢ÊÍ
204                     is_comment = true;
205                     token[cnt++] = ch;
206                     ch = buf[pos++];
207                     while(ch != '
'){
208                         token[cnt++] = ch;
209                         ch = buf[pos++];
210                     }
211                     syn = -2;
212                 }
213                 else if(buf[pos] == '*'){
214                     //¿é×¢ÊÍ
215                     is_comment = true;
216                     while(buf[pos] != '*' || buf[pos + 1] != '/'){
217                         token[cnt++] = ch;
218                         ch = buf[pos++];
219                     }
220                     token[cnt++] = buf[pos++];
221                     token[cnt++] = buf[pos++];
222                     syn = -2;
223                 }
224                 else{
225                     syn = 25;
226                 }
227                 break;
228             case '(':
229                 syn = 26;
230                 break;
231             case ')':
232                 syn = 27;
233                 break;
234             case '{':
235                 syn = 28;
236                 break;
237             case '}':
238                 syn = 29;
239                 break;
240             case ',':
241                 syn = 30;
242                 break;
243             case ';':
244                 syn = 31;
245                 break;
246             case '!':
247                 token[cnt++] = ch;
248                 ch = buf[pos++];
249                 if(ch != '=') {
250                     pos--;
251                     return -1;
252                 }
253                 syn = 37;
254             case '#':
255                 syn = 0;
256                 break;
257         }
258         if(!is_comment){
259             token[cnt++] = ch;
260         }
261         //print(syn, token);
262         return syn;
263     }
264 }
265 
266 void print(int syn, char token[]){
267     if(syn != 20){
268         printf("(%d, %s)
", syn, token);
269     }else{
270         double x = integer;
271         double y = decimal;
272         while(abs(y) > 1){
273             y = y * 0.1;
274         }
275         double z = pow(10, _index);
276         x = (x + y) * z;
277         printf("(%d, %g)
", syn, x);
278     }
279     //words.push_back(Word(syn, integer, decimal, _index, token));
280 }
281 
282 int main()
283 {
284 #ifdef OPEN_FILE
285       freopen("in.txt", "r", stdin);
286     //freopen("out.txt", "w", stdout);
287 #endif // OPEN_FILE
288     read();
289     pos = 0;
290     syn = INF;
291     words.clear();
292     while(pos < len){
293         syn = scaner();
294         if(syn == -1){
295             error();
296             return 0;
297         }
298         else if(syn == -2){
299             continue;
300         }
301         else{
302             words.push_back(Word(syn, integer, decimal, _index, token));
303             print(syn, token);
304         }
305     }
306 }
    View Code

    语法分析器

      1 /*======================================================
  2 #
  3 # author: macan
  4 #
  5 # email: macinchang@gmail.com
  6 #
  7 # created time 2015-10-22 18:42:13
  8 #
  9 # last modified: 2015-10-22 18:42
 10 #
 11 # filename: main.cpp
 12 #
 13 =====================================================*/
 14 #include <bits/stdc++.h>
 15 using namespace std;
 16 #define OPEN_FILE
 17 #define MAXN 101
 18 #define INF 0x3f3f3f3f
 19 bool express();
 20 
 21 struct Word{
 22     int syn, integer, decimal, _index;
 23     char *v;
 24     //Word(){};
 25     Word(int syn = 0, int integer = 0, int decimal = 0, int  _index = 0, char *v = NULL):syn(syn), integer(integer), decimal(decimal), _index(_index), v(v){};
 26 };
 27 vector<Word> words;
 28 char *keyword[10]= {"main", "begin", "int", "float", "double", "char", "if", "else", "do", "while"};
 29 char token[MAXN];
 30 vector<char> buf;
 31 int integer, decimal, _index, cnt;
 32 int syn, last, pos, len;
 33 bool wrong;
 34 
 35 void read() {
 36     char ch;
 37     buf.clear();
 38     while(~scanf("%c", &ch)){
 39         buf.push_back(ch);
 40         if(ch == '#') break;
 41     }
 42     len = buf.size();
 43     if(buf[len - 1] != '#'){
 44         buf.push_back('#');
 45         len++;
 46     }
 47 }
 48 
 49 void error(){
 50     printf("Whoops! Looks like something went wrong...
");
 51     wrong = true;
 52 }
 53 
 54 int iskeyword(char *s){
 55     for(int i = 0; i < 10; i++){
 56         if(strcmp(s, keyword[i]) == 0){
 57             return i + 1;
 58         }
 59     }
 60     return 0;
 61 }
 62 
 63 bool isnumber(char ch){
 64     return ch >= '0' && ch <= '9';
 65 }
 66 
 67 void init(){
 68     last = syn;
 69     integer = decimal = _index = 0;
 70     memset(token, 0, sizeof(token));
 71     cnt = 0;
 72 }
 73 
 74 int scaner(){
 75     int flag = 0;
 76     char ch = buf[pos++];
 77     while(ch == ' ' || ch == '
' || ch == '	'){
 78         if(pos >= len) return 0;
 79         ch = buf[pos++];
 80     }
 81     while(ch != 0){
 82         if(flag == 0) init();
 83         if(isalpha(ch) != 0){
 84             token[cnt++] = ch;
 85             ch = buf[pos++];
 86             while(isalnum(ch)){
 87                 token[cnt++] = ch;
 88                 ch = buf[pos++];
 89             }
 90             syn = iskeyword(token);
 91             if(syn == 0){
 92                 syn = 10;
 93             }
 94             pos--;
 95             return syn;
 96         }
 97         if(isnumber(ch)){
 98             integer = decimal = _index = 0;
 99             integer = ch - '0';
100             token[cnt++] = ch;
101             ch = buf[pos++];
102             while(isnumber(ch)){
103                 integer = integer * 10 + (ch - '0');
104                 token[cnt++] = ch;
105                 ch = buf[pos++];
106             }
107             if(flag)    integer *= flag;
108             if(ch == '.'){
109                 token[cnt++] = ch;
110                 ch = buf[pos++];
111                 if(!isnumber(ch)) return -1;
112                 decimal = 0;
113                 while(isnumber(ch)){
114                     decimal = decimal * 10 + (ch - '0');
115                     token[cnt++] = ch;
116                     ch = buf[pos++];
117                 }
118             }
119             if(flag)    decimal *= flag;
120             if(ch == 'e'){
121                 int p = 1;
122                 token[cnt++] = ch;
123                 ch = buf[pos++];
124                 if(ch == '+' || ch == '-'){
125                     token[cnt++] = ch;
126                     p = ch == '-' ? -1 : 1;
127                     ch = buf[pos++];
128                 }
129                 if(!isnumber(ch)) return -1;
130                 _index = 0;
131                 while(isnumber(ch)){
132                     _index = _index * 10 + (ch - '0');
133                     token[cnt++] = ch;
134                     ch = buf[pos++];
135                 }
136                 _index *= p;
137             }
138             syn = 20;
139             flag = true;
140             //print(syn, token);
141             pos--;
142             return syn;
143         }
144 
145         if(ch == '+' || ch == '-'){
146             token[cnt++] = ch;
147             syn = ch == '+' ? 22 : 23;
148             ch = buf[pos];
149             if(last != 20 && last != 10 && isnumber(ch)){
150                 flag = syn == 22 ? 1 : -1;
151                 pos++;
152                 continue;
153             }
154            // print(syn, token);
155             return syn;
156         }
157         if(ch == '<'){
158             token[cnt++] = ch;
159             ch = buf[pos++];
160             if(ch == '='){
161                 token[cnt++] = ch;
162                 syn = 35;
163             }else{
164                 pos--;
165                 syn = 34;
166             }
167             //print(syn, token);
168             return syn;
169         }
170         if(ch == '>'){
171             token[cnt++] = ch;
172             ch = buf[pos++];
173             if(ch == '='){
174                 token[cnt++] = ch;
175                 syn = 33;
176             }else{
177                 pos--;
178                 syn = 32;
179             }
180             //print(syn, token);
181             return syn;
182         }
183         if(ch == '='){
184             token[cnt++] = ch;
185             ch = buf[pos++];
186             if(ch == '='){
187                 token[cnt++] = ch;
188                 syn = 36;
189             }else{
190                 pos--;
191                 syn = 21;
192             }
193             //print(syn, token);
194             return syn;
195         }
196         bool is_comment = false;
197         switch(ch){
198             case '*':
199                 syn = 24;
200                 break;
201             case '/':
202                 if(buf[pos] == '/'){
203                     //ÐÐ×¢ÊÍ
204                     is_comment = true;
205                     token[cnt++] = ch;
206                     ch = buf[pos++];
207                     while(ch != '
'){
208                         token[cnt++] = ch;
209                         ch = buf[pos++];
210                     }
211                     syn = -2;
212                 }
213                 else if(buf[pos] == '*'){
214                     //¿é×¢ÊÍ
215                     is_comment = true;
216                     while(buf[pos] != '*' || buf[pos + 1] != '/'){
217                         token[cnt++] = ch;
218                         ch = buf[pos++];
219                     }
220                     token[cnt++] = buf[pos++];
221                     token[cnt++] = buf[pos++];
222                     syn = -2;
223                 }
224                 else{
225                     syn = 25;
226                 }
227                 break;
228             case '(':
229                 syn = 26;
230                 break;
231             case ')':
232                 syn = 27;
233                 break;
234             case '{':
235                 syn = 28;
236                 break;
237             case '}':
238                 syn = 29;
239                 break;
240             case ',':
241                 syn = 30;
242                 break;
243             case ';':
244                 syn = 31;
245                 break;
246             case '!':
247                 token[cnt++] = ch;
248                 ch = buf[pos++];
249                 if(ch != '=') {
250                     pos--;
251                     return -1;
252                 }
253                 syn = 37;
254             case '#':
255                 syn = 0;
256                 break;
257         }
258         if(!is_comment){
259             token[cnt++] = ch;
260         }
261         //print(syn, token);
262         return syn;
263     }
264 }
265 
266 void print(int syn, char token[]){
267     if(syn != 20){
268         printf("(%d, %s)
", syn, token);
269     }else{
270         double x = integer;
271         double y = decimal;
272         while(abs(y) > 1){
273             y = y * 0.1;
274         }
275         double z = pow(10, _index);
276         x = (x + y) * z;
277         printf("(%d, %g)
", syn, x);
278     }
279     //words.push_back(Word(syn, integer, decimal, _index, token));
280 }
281 
282 
283 
284 bool factor(){
285     //26 - (
286     if(syn == 26){
287         syn = words[pos++].syn;
288         if(!express()) return false;
289         if(syn == 27){
290             syn = words[pos++].syn;
291             return true;
292         }else{
293             return false;
294         }
295     }
296     else if(syn == 10 || syn == 20){
297         syn = words[pos++].syn;
298         return true;
299     }
300     return false;
301 }
302 
303 bool item(){
304     if(!factor()) return false;
305     //24 -> *, 25 -> /
306     while(syn == 24 || syn == 25){
307         syn = words[pos++].syn;
308         if(!factor()) return false;
309     }
310     return true;
311 }
312 
313 bool express(){
314     if(!item()) return false;
315     //22 -> +, 23 -> -
316    // if(syn != 22 && syn != 23) return false;
317     while(syn == 22 || syn == 23){
318         syn = words[pos++].syn;
319         if(!item()) return false;
320     }
321     return true;
322 }
323 
324 int main()
325 {
326 #ifdef OPEN_FILE
327       freopen("in.txt", "r", stdin);
328     //freopen("out.txt", "w", stdout);
329 #endif // OPEN_FILE
330     read();
331     pos = 0;
332     syn = INF;
333     words.clear();
334     while(pos < len){
335         syn = scaner();
336         if(syn == -1){
337             error();
338             return 0;
339         }
340         else if(syn == -2){
341             continue;
342         }
343         else{
344             words.push_back(Word(syn, integer, decimal, _index, token));
345             print(syn, token);
346         }
347     }
348     /*------------------------------------------
349     |   express => item { + item | - item}
350     |   item => factor { * factor | / factor}
351     |   factor => ID | num | express
352     |   num => (+ | - | @) digit digit* (.digit digit*) | @) (e (+　| - | @) digit digit* | @)
353     |   ID => letter(letter | digit)
354     |   letter => a | b　... | Z
355     |   digit => 1 | 2 ... | 9
356     |-----------------------------------------*/
357     pos = 0;
358     int m = words.size();
359     //words.push_back(Word(-1));
360     syn = words[pos++].syn;
361     if(express()){
362         printf("Yes
");
363     }
364     else{
365         printf("No
");
366     }
367 }
    View Code
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  • 原文地址：https://www.cnblogs.com/macinchang/p/4660475.html
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