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  • 9.28-10.04

    /主要是图算法方面的， BFS. DFS. 生成树. 最短路径. 二分图. 最大流. 差分约束之类。

    1.Catch That Cow

     1 //直接BFS即可。 注意n>k的情况
 2 #include <iostream>
 3 #include <string>
 4 #include <cstdio>
 5 #include <cstring>
 6 #include <algorithm>
 7 #include <queue>
 8 #include <vector>
 9 #include <set>
10 #include <map>
11 #include <cstdlib>
12 
13 using namespace std;
14 
15 int n, k;
16 
17 int main()
18 {
19     int ans = 1000000000;
20     while (~scanf("%d%d", &n, &k))
21     {
22         ans = abs(n-k);
23         if (n >= k)
24         {
25             printf("%d
", ans);
26             continue;
27         }
28         queue<pair<int, int> > qu;
29         while (!qu.empty()) qu.pop();
30         set<int> st;
31         qu.push(make_pair(n, 0));
32         st.insert(n);
33         while (!qu.empty())
34         {
35             int fir = qu.front().first;
36             int sec = qu.front().second;
37             if (ans <= sec) break;
38             if (fir == k)
39             {
40                 ans = sec;
41                 break;
42             }
43             else if (fir < k)
44             {
45                 if (st.count(fir-1) == 0) qu.push(make_pair(fir-1, sec+1)), st.insertfir-1);
46                 if (st.count(fir*2) == 0) qu.push(make_pair(2*fir, sec+1)), st.insert(2*fir);
47                 if (st.count(fir+1) == 0) qu.push(make_pair(fir+1, sec+1)), st.insert(fir+1);
48             }
49             else ans = min(fir-k+sec, ans);
50             qu.pop();
51         }
52         printf("%d
", ans);
53     }
54         
55     return 0;
56 }
    View Code

     2.Children of the Candy Corn

      1 //Left && Right分着写的，懒得再合起来了。BFS即可。
  2 #include <iostream>
  3 #include <string>
  4 #include <cstdio>
  5 #include <cstring>
  6 #include <algorithm>
  7 #include <queue>
  8 #include <vector>
  9 #include <set>
 10 #include <map>
 11 #include <cstdlib>
 12 
 13 using namespace std;
 14 
 15 const int maxn = 45;
 16 char g[maxn][maxn];
 17 int vis[maxn][maxn];
 18 int t, m, n;
 19 int sx, sy, ex, ey;
 20 
 21 void init()
 22 {
 23     for (int i = 0 ; i < maxn; ++i)
 24         for (int j = 0; j < maxn; ++j)
 25             g[i][j] = '#';
 26 }
 27 
 28 int workLeft()
 29 {
 30     int dir[4][2] = {{0, 1}, {1, 0}, {0, -1}, {-1, 0}};
 31     int p = 0, x = sx, y = sy, d = 1;
 32     if (sx == 1) p = 0;
 33     else if (sy == n) p = 1;
 34     else if (sx == m) p = 2;
 35     else p = 3;
 36     while (x != ex || y != ey)
 37     {
 38         d++;
 39         for (int i = 0; i < 4; ++i)
 40         {
 41             int xx = x + dir[(n+4-1)%4][0];
 42             int yy = y + dir[(n+4-1)%4][1];
 43             if (g[xx][yy] != '#') 
 44             {
 45                 x = xx, y = yy, n = (n+4-1)%4;
 46                 break;
 47             }
 48             else n = (n+1)%4;
 49         }
 50     }
 51     return d;
 52 }
 53 
 54 int workRight()
 55 {
 56     int dir[4][2] = {{0, -1}, {1, 0}, {0, 1}, {-1, 0}};
 57     int x = sx, y = sy, d = 1;
 58     int p = 0;
 59     if (sx == 0) p = 0;
 60     else if (sy == 1) p = 1;
 61     else if (sx == m) p = 2;
 62     else p = 3;
 63     while (x != ex || y != ey)
 64     {
 65         d++;
 66         for (int i = 0; i < 4; ++i)
 67         {
 68             int xx = x + dir[(n+4-1)%4][0];
 69             int yy = y + dir[(n+4-1)%4][1];
 70             if (g[xx][yy] != '#')
 71             {
 72                 x = xx, y = yy, n = (n+4-1)%4;
 73                 break;
 74             }
 75             else n = (n+1)%4;
 76         }
 77     }    
 78     return d;
 79 }
 80 
 81 int workBest()
 82 {
 83     int dir[4][2] = {{1, 0}, {-1, 0}, {0, 1}, {0, -1}};
 84     memset(vis, 0, sizeof(vis));
 85     queue<pair<pair<int, int>, int> > qu;
 86     qu.push(make_pair(make_pair(sx, sy), 1));
 87     vis[sx][sy] = 1;
 88      while (!qu.empty())
 89     {
 90         int x = qu.front().first.first;
 91         int y = qu.front().first.second;
 92         int d = qu.front().second;
 93         qu.pop();
 94         if (x == ex && y == ey) return d;
 95         for (int i = 0; i < 4; ++i)
 96         {
 97             int xx = x + dir[i][0];
 98             int yy = y + dir[i][1];
 99             if (!vis[xx][yy] && g[xx][yy] != '#')
100             {
101                 qu.push(make_pair(make_pair(xx, yy), d+1));
102                 vis[xx][yy] = 1;        
103             }
104         }
105     }
106 }
107 
108 int main()
109 {
110     scanf("%d", &t);
111     while (t--)
112     {
113         init();
114         scanf("%d%d", &n, &m);
115         for (int i = 1; i <= m; ++i)
116         {
117             getchar();
118             for (int j = 1; j <= n; ++j)
119             {
120                 scanf("%c", &g[i][j]);
121                 if (g[i][j] == 'S')
122                     sx = i, sy = j;
123                 if (g[i][j] == 'E')
124                     ex = i, ey = j;
125             }
126         }
127         printf("%d %d %d
", workLeft(), workRight(), workBest());
128     }    
129 
130     return 0;
131 }
    View Code

     3.Currency Exchange

     1 //Bellman-Ford的变形
 2 #include <iostream>
 3 #include <string>
 4 #include <cstdio>
 5 #include <cstring>
 6 #include <algorithm>
 7 #include <queue>
 8 #include <vector>
 9 #include <set>
10 #include <map>
11 #include <cstdlib>
12 
13 using namespace std;
14 
15 const int maxn = 105;
16 
17 class Node
18 {
19 public:
20     int a, b;
21     double r, c;    
22     Node(int aa, int bb, double rr, double cc): a(aa), b(bb), r(rr), c(cc){}
23 };
24 
25 vector<Node> vec;
26 double dis[maxn];
27 double v;
28 int n, m, s;
29 
30 void bellmanFord()
31 {
32     memset(dis, 0, sizeof(dis));
33     dis[s] = v;
34     for (int i = 1; i <= n-1; ++i)
35     {
36         for (int j = 0; j < vec.size(); ++j)
37             dis[vec[j].b] = max(dis[vec[j].b] ,(dis[vec[j].a]-vec[j].c)*vec[j].r);
38     }
39     
40     for (int i = 0; i < vec.size(); ++i)
41     {
42         if (dis[vec[i].b] < (dis[vec[i].a]-vec[i].c)*vec[i].r)
43         {
44             printf("YES
");
45             return ;
46         }
47     }
48     puts("NO");
49 }
50 
51 int main()
52 {
53     while (~scanf("%d%d%d%lf", &n, &m, &s, &v))
54     {
55         vec.clear();
56         int a, b;
57         double r1, c1, r2, c2;
58         for (int i = 0; i < m; ++i)
59         {
60             scanf("%d%d%lf%lf%lf%lf", &a, &b, &r1, &c1, &r2, &c2);
61             Node node1(a, b, r1, c1), node2(b, a, r2, c2);
62             vec.push_back(node1), vec.push_back(node2);
63         }    
64         bellmanFord();
65     }    
66     
67     return 0;
68 }
    View Code

     4.Wormholes

     1 //依旧是BellmanFord即可，不过题目数据太差了，n的数据量不是500，所以开大dis数组即可。
 2 #include <iostream>
 3 #include <string>
 4 #include <cstdio>
 5 #include <cstring>
 6 #include <algorithm>
 7 #include <queue>
 8 #include <vector>
 9 #include <set>
10 #include <map>
11 #include <cstdlib>
12 
13 using namespace std;
14 
15 #define INF 1e9
16 const int maxn = 10015;
17 
18 class Lode
19 {
20 public:
21     int s, e, t;
22     Node(int ss, int ee, int tt): s(ss), e(ee), t(tt){}
23 };
24 vector<Node> vec;
25 int f, n, m, w;
26 int dis[maxn];
27 
28 void init()
29 {
30     vec.clear();
31     for (int i = 0; i < maxn; ++i)
32         dis[i] = INF;
33 }
34 
35 void bellmanFord()
36 {
37     dis[1] = 0;
38     for (int i = 1; i < n-1; ++i)
39     {
40         for (int j = 0; j < vec.size(); ++j)
41             dis[vec[j].e] = min(dis[vec[j].e], dis[vec[j].s]+vec[j].t);
42     }
43     for (int i = 0; i < vec.size(); ++i)
44     {
45         if (dis[vec[i].e] > dis[vec[i].s] + vec[i].t)
46         {
47             puts("YES");
48             return ;
49         }
50     }
51     puts("NO");
52 }
53 
54 int main()
55 {
56     scanf("%d", &f);
57     while (f--)
58     {
59         init();
60         scanf("%d%d%d", &n, &m, &w);
61         int s, e, t;
62         for(int i = 0; i < m; ++i)
63         {
64             scanf("%d%d%d", &s, &e, &t);
65             Node node1(s, e, t);
66             vec.push_back(node1);
67             Node node2(e, s, t);
68             vec.push_back(node2);             
69         }
70         for (int i = 0; i < w; ++i)
71         {
72             scanf("%d%d%d", &s, &e, &t);
73             Node node(s, e, -t);
74             vec.push_back(node);
75         }
76         bellmanFord();
77     }
78         
79     return 0;
80 }
    View Code

     5.昂贵的聘礼

     1 #include <iostream>
 2 #include <string>
 3 #include <cstdio>
 4 #include <cstring>
 5 #include <algorithm>
 6 #include <queue>
 7 #include <vector>
 8 #include <set>
 9 #include <map>
10 #include <cstdlib>
11 
12 using namespace std;
13 
14 #define INF 1e9
15 const int maxn = 105;
16 
17 int price[maxn], g[maxn][maxn], level[maxn];
18 int dis[maxn], vis[maxn];
19 int n, m, ans;
20 
21 void init()
22 {
23     memset(price, 0, sizeof(price));
24     memset(level, 0, sizeof(level));
25     for (int i = 0; i <= n; ++i)
26         for (int j = 0; j <= n; ++j)
27             g[i][j] = INF;
28 }
29 
30 int dijkstra()
31 {
32     for (int i = 1; i <= n; ++i)
33         dis[i] = price[i];
34     for (int i = 1; i <= n; ++i)
35     {
36         int temp = INF, x;
37         for (int j = 1; j <= n; ++j)
38             if (!vis[j] && dis[j] < temp)
39                 temp = dis[x = j];
40         vis[x] = 1;
41         for (int j = 1; j <= n; ++j)
42             if (dis[x]+g[x][j] < dis[j] && !vis[j])
43                 dis[j] = dis[x]+g[x][j];
44     }
45     return dis[1];
46 }
47 
48 int main()
49 {
50     while (~scanf("%d%d", &m, &n))
51     {
52         init();
53         for (int i = 1; i <= n; ++i)
54         {
55             int x;
56             scanf("%d%d%d", &price[i], &level[i], &x);
57             for (int j = 0; j < x; ++j)
58             {
59                 int t, v;
60                 scanf("%d%d", &t, &v);
61                 g[t][i] = v;
62             }
63             g[0][i] = price[i];
64         }
65         ans = INF;
66         for (int i = 1; i <= n; ++i)
67         {
68             int minl = level[i];
69             for<span> (int j = 1; j <= n; ++j)
70             {
71                 if (level[j]-minl > m || minl > level[j]) vis[j] = 1;
72                 else vis[j] = 0;
73             }
74             int now = dijkstra();
75             ans = min(now, ans);
76         }
77         printf("%d
", ans);
78     }
79 
80     return 0;
81 }
    View Code

     6.Intervals

     1 //差分约束系统，差分约数系统的含义，其实就是如果有n个变量在m个形如aj-ai>=bk条件下，求解的此不等式的方法。而这种不等式的解法其实就是转化为图论的最小路的算法求解的。
 2 根据题意可得不等式//Sbi - Sai >= ci//Si - Si-1 >= 0//Si-1 - Si >= -1
 3 #include <iostream>
 4 #include <string>
 5 #include <cstdio>
 6 #include <cstring>
 7 #include <algorithm>
 8 #include <queue>
 9/span> #include <vector>
10 #include <set>
11 #include <map>
12 #include <cstdlib>
13 
14 using namespace std;
15 
16 #define INF 1000000007
17 #define MIN(a, b) (a > b ? b : a)
18 #define MAX(a, b) (a > b ? a : b)
19 #define MAXN 50005
20 const int maxn = 50005;
21 struct Edge
22 {
23     int v;
24     int w;
25     int next;
26 }edge[MAXN*3];
27 int head[MAXN], d[MAXN], vis[MAXN];
28 int n, t, source, target;
29 
30 void init()
31 {
32     memset(edge, 0, sizeof(edge));
33     memset(vis, 0, sizeof(vis));
34     memset(head, -1, sizeof(head));
35     t = 0;
36     source = INF, target = -INF;
37 }
38 
39 void addEdge(int u, int v, int w)
40 {
41     edge[t].v = v;
42     edge[t].w = w;
43     edge[t].next = head[u];
44     head[u] = t++;
45 }
46 
47 void spfa()
48 {
49     for (int i = source; i <= target; ++i) d[i] = -INF;
50     d[source] = 0;
51     queue<int> qu;
52     qu.push(source);
53     while (!qu.empty())
54     {
55         int x = qu.front();
56         qu.pop();
57         vis[x] = 0;
58         for (int e = head[x]; e != -1; e = edge[e].next)
59             if (d[edge[e].v] < d[x]+edge[e].w)
60             {
61                 d[edge[e].v] = d[x] + edge[e].w;
62                 if (!vis[edge[e].v])
63                 {
64                     qu.push(edge[e].v);
65                     vis[edge[e].v] = 1;
66                 }
67             }
68     }
69 }
70 
71 int main()
72 {
73     int u, v, w;
74     init();
75     scanf("%d", &n);
76     for (int i = 0; i < n; ++i)
77     {
78         scanf("%d%d%d", &u, &v, &w);
79         addEdge(u, v+1, w);
80         source = min(u, source);
81         target = max(v+1, target);
82     }
83     for (int i = source; i < target; ++i)
84     {
85         addEdge(i, i+1, 0);
86         addEdge(i+1, i, -1);    
87     }
88     spfa();
89     printf("%d
", d[target]);
90     
91     return 0;
92 }
    View Code

     7.World Exhibition

      1 //差分约束，脑残了，一开始一直拿着带输出测试数据的代码提交，一直wa。。。隐含条件Aj-Ai=无穷大，Ai-Aj<=0
  2 #include <iostream>
  3 #include <string>
  4 #include <cstdio>
  5 #include <cstring>
  6 #include <algorithm>
  7 #include <queue>
  8 #include <vector>
  9 #include <set>
 10 #include <map>
 11 #include <cstdlib>
 12 
 13 using namespace std;
 14 
 15 #define INF 1000000007
 16 #define MIN(a, b) (a > b ? b : a)
 17 #define MAX(a, b) (a > b ? a : b)
 18 #define MAXN 1005
 19 #define maxn 10005
 20 struct Edge
 21 {
 22     int v;
 23     int w;
 24     int next;
 25 }edge[maxn*3];
 26 int vis[MAXN], d[MAXN], head[MAXN], use[MAXN];
 27 int t, T, n;
 28 
 29 void init()
 30 {
 31     t = 0;
 32     memset(edge, 0, sizeof(edge));
 33     for (int i = 0; i < MAXN; ++i)
 34         use[i] = 0, vis[i] = 0, d[i] = INF, head[i] = -1;
 35 }
 36 
 37 void addEdge(int u, int v, int w)
 38 {
 39     edge[t].v = v;
 40     edge[t].w = w;
 41     edge[t].next = head[u];
 42     head[u] = t++;    
 43 }
 44 
 45 int spfa()
 46 {
 47     queue<int> qu;
 48     while (!qu.empty()) qu.pop();
 49     d[1] = 0;
 50     qu.push(1);
 51     while (!qu.empty())
 52     {
 53         int x = qu.front();
 54         qu.pop();
 55         vis[x] = 0;
 56         for (int e = head[x]; e != -1; e = edge[e].next)
 57         {
 58             if (d[edge[e].v] > d[x]+edge[e].w)
 59             {
 60                 d[edge[e].v] = d[x]+edge[e].w;
 61                 if (!vis[edge[e].v])
 62                 {
 63                     qu.push(edge[e].v);
 64                     vis[edge[e].v] = 1;
 65                     if (++use[edge[e].v] > n) return -1;
 66                 }
 67             }
 68         }    
 69     }
 70     if (d[n] == INF) return -2;
 71     return d[n];
 72 }
 73 
 74 int main()
 75 {
 76     scanf("%d", &T);
 77     while (T--)
 78     {
 79         init();
 80         int x, y;
 81         scanf("%d%d%d", &n, &x, &y);
 82         int a, b, c;
 83         for (int i = 0; i < x; ++i)
 84         {
 85             scanf("%d%d%d", &a, &b, &c);
 86             addEdge(a, b, c);
 87         }
 88         for (int i = 0; i < y; ++i)
 89         {
 90             scanf("%d%d%d", &a, &b, &c);
 91             addEdge(b, a, -c);
 92         }
 93         for (int i = 2; i <= n; ++i)
 94         {
 95             addEdge(i-1, i, INF);
 96             addEdge(i, i-1, 0);
 97         }
 98         printf("%d
", spfa());
 99     }    
100     
101     return 0;
102 }
    View Code

     8.Schedule Problem

      1 //差分约束，构建不等式然后选取最长路。我觉得这题不严谨。。比如FAF 1 2  2 1，我觉得应该是impossible...但是。。。
  2 #include <iostream>
  3 #include <cstdio>
  4 #include <algorithm>
  5 #include <string>
  6 #include <cstring>
  7 #include <set>
  8 #include <stdint.h>
  9 #include <utility>
 10 #include <map>
 11 #include <cstdlib>
 12 #include <queue>
 13 #include <vector>
 14 #include <numeric>
 15 #include <list>
 16 #include <bitset>
 17 #include <exception>
 18 #include <istream>
 19 #include <ostream>
 20 #include <stdexcept>
 21 #include <functional>
 22 #include <stack>
 23 #include <unordered_set>
 24 
 25 #define LL long long int
 26 using namespace std;
 27 
 28 
 29 #define MEM memset
 30 #define MAX (a > b ? a : b)
 31 #define MIN (a < b ? a : b)
 32 #define MAXN 200000
 33 #define LL long long int
 34 #define INF 1000000007
 35 
 36 struct Edge
 37 {
 38     int v;
 39     int w;
 40     int next;
 41 }edge[MAXN];
 42 int d[MAXN], vis[MAXN], use[MAXN], weight[MAXN], head[MAXN], in[MAXN];
 43 int ncas, n, t, a1, a2;
 44 char ch[10];
 45 
 46 void init()
 47 {
 48     t = 0;
 49     memset(edge, 0, sizeof(edge));
 50     for (int i = 0; i < MAXN; ++i)
 51         vis[i] = weight[i] = use[i] = in[i] = 0, d[i] = -INF, head[i] = -1;
 52 }
 53 
 54 void addEdge(int u, int v, int w)
 55 {
 56     edge[t].v = v;
 57     edge[t].w = w;
 58     edge[t].next = head[u];
 59     head[u] = t++;
 60 }
 61 
 62 void judge()
 63 {
 64     in[a1]++;
 65     if (strcmp(ch,"SAF") == 0) addEdge(a2, a1, weight[a2]);
 66     else if (strcmp(ch, "FAF") == 0) addEdge(a2, a1, weight[a2]-weight[a1]);
 67     else if (strcmp(ch, "FAS") == 0) addEdge(a2, a1, -weight[a1]);
 68     else addEdge(a2, a1, 0);
 69 }
 70 
 71 int spfa()
 72 {
 73     int s = 0;
 74     queue<int> qu;
 75     while (!qu.empty()) qu.pop();
 76     d[s] = 0;
 77     qu.push(s);
 78     vis[s] = 1;
 79     while (!qu.empty())
 80     {
 81         int x = qu.front();
 82         qu.pop();
 83         vis[x] = 0;
 84         use[x]++;
 85         if (use[x] > n) return 1;
 86         for (int e = head[x]; e != -1; e = edge[e].next)
 87         {
 88             if (d[edge[e].v] < d[x]+edge[e].w)
 89             {
 90                 d[edge[e].v] = d[x]+edge[e].w;
 91                 if (!vis[edge[e].v])
 92                 {
 93                     qu.push(edge[e].v);
 94                     vis[edge[e].v] = 1;
 95                 }
 96             }
 97         }
 98     }
 99     for (int i = 1; i <= n; ++i)
100         printf("%d %d
", i, d[i]);
101     return 0;
102 }
103 
104 int main()
105 {
106     ncas = 1;
107     while (~scanf("%d", &n) && n)
108     {
109         init();
110         for (int i = 1; i <= n; ++i)
111             scanf("%d", &weight[i]);
112         while (scanf("%s", ch) && ch[0] != '#')
113         {
114             scanf("%d %d", &a1, &a2);
115             judge();
116         }
117         for (int i = 1; i <= n; ++i)
118             addEdge(0, i, 0);
119         printf("Case %d:
", ncas++);
120         if (spfa()) puts("impossible");
121         puts("");
122     }
123 
124     return 0;
125 }
    View Code

     9.Truck History

     1 //Prim算法
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <algorithm>
 5 #include <string>
 6 #include <cstring>
 7 #include <set>
 8 #include <utility>
 9 #include <map>
10 #include <cstdlib>
11 #include <queue>
12 #include <vector>
13 #include <numeric>
14 #include <list>
15 #include <bitset>
16 #include <exception>
17 #include <istream>
18 #include <ostream>
19 #include <qtdexcept>
20 #include <functional>
21 #include <stack>
22 
23 #define LL long long int
24 using namespace std;
25 
26 
27 #define MEM memset
28 #define MAX (a > b ? a : b)
29 #define MIN (a < b ? a : b)
30 #define MAXN 2010
31 #define LL long long int
32 #define INF 1000000007
33 
34 int g[MAXN][MAXN];
35 int d[MAXN], vis[MAXN];
36 char ch[MAXN][10];
37 int n;
38 
39 void init()
40 {
41     memset(vis, 0, sizeof(vis));
42     for (int i = 0; i < n; ++i)
43         for (int j = 0; j < n; ++j)
44         {
45             if (i == j) g[i][j] = 0;
46             else
47             {
48                 int cnt = 0;
49                 for (int k = 0; k < 7; ++k)
50                     if (ch[i][k] != ch[j][k]) cnt++;
51                 g[i][j] = g[j][i] = cnt;
52             }
53         }
54     for (int i = 0; i < n; ++i)
55         d[i] = g[0][i];
56 }
57 
58 int prim()
59 {
60     init();
61     int k = 0, idx, len, ans = 0;
62     vis[k] = 1;
63     for (int i = 1; i < n; ++i)
64     {
65         len = INF;
66         for (int j = 0; j < n; ++j)
67             if (!vis[j] && d[j] < len)
68                 len = d[idx = j];
69         ans += len;
70         vis[idx] = 1;
71         for (int j = 0; j < n; ++j)
72             if (!vis[j] && g[idx][j] < d[j])
73                 d[j] = g[idx][j];
74     }
75     return ans;
76 }
77 
78 int main()
79 {
80     while (~scanf("%d", &n) && n)
81     {
82         for (int i = 0; i < n; ++i)
83             scanf("%s", ch[i]);
84         printf("The highest possible quality is 1/%d.
", prim());
85     }
86 
87     return 0;
88 }
    View Code

     10.Highways

     1 //Prim算法
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #include <string>
 7 #include <cstring>
 8 
 9 using namespace std;
10 
11 #define INF 1000000007
12 #define MAXN 505
13 #define MAX(a, b) (a > b ? a : b)
14 #define MIN(a, b) (a < b ? a : b)
15 
16 int t, n;
17 int d[MAXN], vis[MAXN];
18 int g[MAXN][MAXN];
19 
20 void init()
21 {
22     for (int i = 0; i < n; ++i)
23         d[i] = g[0][i], vis[i] = 0;
24 }
25 
26 int prim()
27 {
28     init();
29     int ans = -INF;
30     vis[0] = 1;
31     for (int i = 1; i < n; ++i)
32     {
33         int min_cost = INF, idx = 0;
34         for (int j = 0; j < n; ++j)
35             if (!vis[j] && d[j] < min_cost)
36                 min_cost = d[idx = j];
37         ans = max(ans, min_cost);
38         vis[idx] = 1;
39         for (int j = 0; j < n; ++j)
40             if (!vis[j] && d[j] > g[idx][j])
41                 d[j] = g[idx][j];
42     }
43     return ans;
44 }
45 
46 int main()
47 {
48 
49     scanf("%d", &t);
50     while (t--)
51     {
52         scanf("%d", &n);
53         for (int i = 0; i < n; ++i)
54             for (int j = 0; j < n; ++j)
55                 scanf("%d", &g[i][j]);
56         printf("%d
", prim());
57     }
58 
59     return 0;
60 }
    View Code

     11.Agri-Net

     1 //prim算法
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #include <string>
 7 #include <cstring>
 8 
 9 using namespace std;
10 
11 #define INF 1000000007
12 #define MAXN 105
13 #define MAX(a, b) (a > b ? a : b)
14 #define MIN(a, b) (a < b ? a : b)
15 
16 int n;
17 int d[MAXN], vis[MAXN];
18 int g[MAXN][MAXN];
19 
20 void init()
21 {
22     for (int i = 0; i < n; ++i)
23         d[i] = g[0][i], vis[i] = 0;
24 }
25 
26 int prim()
27 {
28     init();
29     int ans = 0;
30     vis[0] = 1;
31     for (int i = 1; i < n; ++i)
32     {
33         int min_cost = INF, idx = 0;
34         for (int j = 0; j < n; ++j)
35             if (!vis[j] && d[j] < min_cost)
36                 min_cost = d[idx = j];
37         ans += min_cost;
38         vis[idx] = 1;
39         for (int j = 0; j < n; ++j)
40             if (!vis[j] && d[j] > g[idx][j])
41                 d[j] = g[idx][j];
42     }
43     return ans;
44 }
45 
46 int main()
47 {
48     while (~scanf("%d", $amp;n))
49     {
50         for (int i = 0; i < n; ++i)
51         for (int j = 0; j < n; ++j)
52             scanf("%d", &g[i][j]);
53         printf("%d
", prim());
54     }
55 
56     return 0;
57 }
    View Code

     12.Agri-Net

     1 //Kruskal算法 与上面prim对比一下
 2 #include <iostream>
 3 #include <cstdio>
 4 #include <cstdlib>
 5 #include <algorithm>
 6 #include <string>
 7 #include <cstring>
 8 
 9 using namespace std;
10 
11 #define INF 1000000007
12 #define MAXN 105
13 #define MAX(a, b) (a > b ? a : b)
14 #define MIN(a, b) (a < b ? a : b)
15 
16 struct Edge
17 {
18     int u;
19     int v;
20     int w;
21 }edge[MAXN*MAXN];
22 int n;
23 int father[MAXN];
24 
25 int cmp(const void* a, const void* b)
26 {
27     return ((Edge*)a)->w - ((Edge*)b)->w;
28 }
29 
30 int findFather(int val)
31 {
32     if (father[val] == val) return val;
33     return father[val] = findFather(father[val]);
34 }
35 
36 void unionFather(int x, int y)
37 {
38     int xx = findFather(x);
39     int yy = findFather(y);
40     father[xx] = father[yy];
41 }
42 
43 int main()
44 {
45     while (~scanf("%d", &n))
46     {
47         for (int i = 0; i < n; ++i)
48             for (int j = 0; j < n; ++j)
49             {
50                 scanf("%d", &edge[i*n+j].w);
51                 edge[i*n+j].u = i, edge[i*n+j].v = j;
52             }
53         for (int i = 0; i < n; ++i) father[i] = i;
54         qsort(edge, n*n, sizeof(Edge), cmp);
55         int ans = 0;
56         for (int i = 0; i < n*n; ++i)
57         {
58             if (edge[i].u >= edge[i].v) continue;
59             if (findFather(edge[i].u) != findFather(edge[i].v))
60             {
61                 ans += edge[i].w;
62                 unionFather(edge[i].u, edge[i].v);
63             }
64         }
65         printf("%d
", ans);
66     }
67 
68     return 0;
69 }
    View Code
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