选择一个区间反转使得1最多
http://codeforces.com/contest/327/problem/A
弱鸡代码
1 #include <bits/stdc++.h> 2 using namespace std; 3 int sum[120], sum2[120], a[120], b[120]; 4 int main(){ 5 int n, ma = -1; 6 cin>>n; 7 for(int i = 1; i <= n; i++){ 8 cin>>a[i]; 9 sum[i] = sum[i-1] + a[i]; 10 b[i] = 1 - a[i]; 11 sum2[i] = sum2[i-1] + b[i]; 12 } 13 for(int i = 1; i <= n; i++){ 14 for(int j = i; j <=n ; j++){ 15 ma = max(sum[i-1] + sum[n] - sum[j] + sum2[j] - sum2[i-1], ma); 16 } 17 } 18 cout<<ma<<endl; 19 }
大神代码
1 #include<iostream> 2 using namespace std; 3 int main() 4 { 5 int n,l=0,k=0,s=0,i,a; 6 cin>>n; 7 for(i=1;i<=n;i++) 8 { 9 cin>>a;if(a==1) {l++;if(s>0) s--;}else s++; if(s>k) k=s; 10 } 11 if(k==0) {cout<<l-1;return 0;} 12 cout<<l+k; 13 }
思路很重要，其实就是找最长的0.。。。。。。。
@找规律题
啦啦啦啦啦~~~从样例里面寻找到新大陆！！
1 2 + 2*1 = 4 ----> 2/2 = 1; 2 2 + 17*2 = 36 ----> 6/3 = 2; 3 3 + 46*3 = 144 ----> 12/4 = 3; 4 12 + 97*4 = 400 ----> 20/5 = 4; 5 so -----------------> 6 X = n*(n+1)*(n+1) - (n-1);
http://codeforces.com/contest/716/problem/C
1 #include <stdio.h> 2 long long x; 3 int main(){ 4 scanf("%I64d", &x); 5 printf("2 ", 2); 6 for(long long i = 2; i <= x; i++) 7 printf("%I64d ", i*(i+1)*(i+1)-(i-1)); 8 }
@ http://codeforces.com/problemset/problem/722/C
逐次删除元素，求区间最大和
1 #include <iostream> 2 using namespace std; 3 #define ll long long 4 const int maxn = 1e5+10; 5 ll a[maxn], sum[maxn], b[maxn], l[maxn], r[maxn], vis[maxn], c[maxn], n, ma; 6 int main(){ 7 std::ios::sync_with_stdio(false); 8 cin.tie(0), cout.tie(0); 9 cin>>n; 10 for(int i = 1; i <= n; i++) cin>>a[i]; 11 for(int i = 1; i <= n; i++) cin>>b[i]; 12 for(int i = n; i > 1; i--){ 13 if(vis[b[i]-1] && vis[b[i]+1]){ 14 r[l[b[i]-1]] = r[b[i]+1], l[r[b[i]+1]] = l[b[i]-1]; 15 ma =sum[r[b[i]-1]] = sum[l[b[i]-1]] = sum[l[b[i]+1]] = sum[r[b[i]+1]] = sum[l[b[i]-1]] + sum[r[b[i]+1]] +a[b[i]]; 16 }else if(vis[b[i]-1]){ 17 l[b[i]] = l[b[i]-1], r[b[i]] = b[i], r[l[b[i]-1]] = b[i]; 18 ma = sum[r[b[i]-1]] = sum[l[b[i]-1]] = sum[l[b[i]]] = sum[r[b[i]]] = sum[l[b[i]-1]] + a[b[i]]; 19 }else if(vis[b[i]+1]){ 20 l[b[i]] = b[i], r[b[i]] = r[b[i]+1], l[r[b[i]+1]] = b[i]; 21 ma = sum[r[b[i]]] = sum[l[b[i]]] = sum[r[b[i]+1]] = sum[l[b[i]+1]] = sum[r[b[i]+1]] + a[b[i]]; 22 }else{ 23 l[b[i]] = r[b[i]] = b[i]; 24 ma = sum[l[b[i]]] = sum[r[b[i]]] = a[b[i]]; 25 } 26 c[i] = max(ma, c[i+1]); 27 vis[b[i]] = 1; 28 } 29 for(int i = 2; i <= n; i++) cout<<c[i]<<endl; 30 cout<<0<<endl; 31 return 0; 32 }
小艾代码：
1 #include <iostream> 2 #include <stdio.h> 3 using namespace std; 4 #define ll long long 5 ll a[100005],numl[100005],numr[100005],b[100005],l[100005],r[100005],ans[100005]; 6 ll Max(ll a,ll b){ 7 return a>b?a:b; 8 } 9 int main(){ 10 int n; 11 long long sum=0; 12 scanf("%d",&n); 13 for(int i=1;i<=n;i++){ 14 scanf("%lld",&a[i]); 15 } 16 for(int i=n;i>=1;i--) scanf("%lld",&b[i]); 17 for(int i=0;i<=n+1;i++){ 18 if(i>0) l[i]=i-1; 19 if(i<n+1) r[i]=i+1; 20 } 21 for(int i=1;i<=n;i++){ 22 int x=b[i]; 23 long long num=numr[l[x]]+numl[r[x]]+a[x]; 24 numl[r[x]]=num; 25 numr[l[x]]=num; 26 l[r[x]]=l[x]; 27 r[l[x]]=r[x]; 28 sum=Max(sum,num); 29 ans[i]=sum; 30 } 31 for(int i=n-1;i>=0;i--) printf("%lld ",ans[i]); 32 33 }
X73代码：
1 #include <bits/stdc++.h> 2 using namespace std; 3 #define ll long long 4 const int N=1e5+5; 5 6 ll a[N],b[N]; 7 ll sum[N],res[N],mark[N]; 8 set<ll>s; 9 int pre[N]; 10 int Find(int v) 11 { 12 if(pre[v]!=v) 13 pre[v]=Find(pre[v]); 14 return pre[v]; 15 } 16 17 int main() 18 { 19 int n; 20 scanf("%d",&n); 21 for(int i=1;i<=n;i++)pre[i]=i; 22 for(int i=1;i<=n;i++)scanf("%I64d",a+i); 23 for(int i=1;i<=n;i++)scanf("%I64d",b+i); 24 res[n]=0; 25 mark[b[n]]=1; 26 sum[b[n]]=a[b[n]]; 27 s.insert(a[b[n]]); 28 for(int i=n-1;i>=1;i--) 29 { 30 res[i]=*s.rbegin(); 31 int t=b[i]; 32 if(mark[t+1]&&!mark[t-1]) 33 { 34 int u=Find(t+1); 35 pre[t]=u; 36 sum[u]+=a[t]; 37 s.insert(sum[u]); 38 } 39 else if(!mark[t+1]&&mark[t-1]) 40 { 41 int u=Find(t-1); 42 pre[t]=u; 43 sum[u]+=a[t]; 44 s.insert(sum[u]); 45 } 46 else if(mark[t+1]&&mark[t-1]) 47 { 48 int u=Find(t+1); 49 int v=Find(t-1); 50 pre[u]=v; 51 pre[t]=v; 52 sum[v]+=sum[u]+a[t]; 53 s.insert(sum[v]); 54 } 55 else 56 { 57 sum[t]+=a[t]; 58 s.insert(a[t]); 59 } 60 mark[t]=1; 61 } 62 for(int i=1;i<=n;i++) 63 printf("%I64d ",res[i]); 64 return 0; 65 }
@ http://codeforces.com/contest/723/problem/D
dfs
1 #include <bits/stdc++.h> 2 using namespace std; 3 char a[60][60]; 4 int flag[60][60], n, m, k, num, t = 0, mark, dir[4][2] = {0,1,1,0,0,-1,-1,0}; 5 pair<int ,pair<int,int> > p[2500]; 6 void dfs(int x, int y){ 7 if(x == 0 || x == n-1 || y == 0 || y == m-1) mark = 0; 8 for(int i = 0; i < 4; i++){ 9 int xx = x + dir[i][0]; 10 int yy = y + dir[i][1]; 11 if(xx >= 0 && xx < n && yy >= 0 && yy < m && a[xx][yy] == '.' && !flag[xx][yy]){ 12 flag[xx][yy] = 1; 13 num++; 14 dfs(xx, yy); 15 } 16 } 17 } 18 void lalala(int x, int y){ 19 a[x][y] = '*'; 20 for(int i = 0; i < 4; i++){ 21 int xx = x + dir[i][0]; 22 int yy = y + dir[i][1]; 23 if(xx >= 0 && xx < n && yy >= 0 && yy < m && a[xx][yy] == '.') lalala(xx,yy); 24 } 25 } 26 int main(){ 27 cin >> n>> m >> k; 28 for(int i = 0; i < n; i++) cin>>a[i]; 29 for(int i = 0; i < n; i++){ 30 for(int j = 0; j < m; j++){ 31 if(a[i][j] == '.' && !flag[i][j]){ 32 flag[i][j] = 1, num = 1, mark = 1, dfs(i,j); 33 if(mark) p[t].first = num, p[t].second.first = i, p[t].second.second = j, t++; 34 } 35 } 36 } 37 sort(p, p+t); 38 int sum = 0; 39 for(int i = 0; i < t-k; i++) sum += p[i].first, lalala(p[i].second.first, p[i].second.second); 40 cout<<sum<<endl; 41 for(int i = 0; i < n; i++) cout<<a[i]<<endl; 42 }
@ http://codeforces.com/contest/722/problem/D
想了很久没有思路。。。垃圾
1 #include <bits/stdc++.h> 2 using namespace std; 3 #define ll long long 4 map<int, int> m; 5 priority_queue<int> pq; 6 int main(){ 7 int n, flag = 0, x; 8 cin>>n; 9 for(int i = 0; i < n; i++){ 10 cin>>x; 11 m[x] = 1; 12 pq.push(x); 13 } 14 while(1){ 15 x = pq.top(); 16 while(x&&m[x]) x/=2; 17 if(!x) break; 18 else pq.pop(),pq.push(x), m[x] = 1; 19 } 20 while(!pq.empty()){ 21 cout<<pq.top()<<" "; 22 pq.pop(); 23 } 24 return 0; 25 }
@ http://codeforces.com/contest/721/problem/C
费用小于等于T游览的城市尽量多
1 #include <iostream> 2 #include <vector> 3 #include <string.h> 4 using namespace std; 5 const int maxn = 5005; 6 int n, m, t; 7 int node = 0, head[maxn], dp[maxn][maxn], parent[maxn][maxn]; 8 struct Node { 9 int from, to, next, w; 10 } Edge[maxn]; 11 void init(){ 12 memset(head, -1, sizeof(head)); 13 for(int i = 0; i <= n; i ++){ 14 for(int j = 0; j <= n; j ++){ 15 dp[i][j] = t+1; 16 } 17 } 18 dp[1][1] = 0; 19 } 20 void addedge(int u, int v, int w){ 21 Edge[node].from = u; 22 Edge[node].to = v; 23 Edge[node].w = w; 24 Edge[node].next = head[u]; 25 head[u] = node ++; 26 } 27 void print(int pos){ 28 cout << pos <<endl; 29 int id = n; 30 vector<int> v; 31 v.push_back(n); 32 for(int i = pos; i > 1; i--){ 33 v.push_back(parent[i][id]); 34 id = parent[i][id]; 35 } 36 for(int i = v.size() - 1; i >= 0; i--) cout << v[i] <<" "; 37 } 38 void solve(){ 39 int v, u, w, pos; 40 for(int i = 2; i <= n; i++){ 41 for(int j = 0; j < m; j++){ 42 u = Edge[j].from, v = Edge[j].to, w = Edge[j].w; 43 if(dp[i-1][u] + w < dp[i][v]){ 44 dp[i][v] = dp[i-1][u] + w; 45 parent[i][v] = u; 46 } 47 } 48 if(dp[i][n] <= t) pos = i; 49 } 50 print(pos); 51 } 52 int main(){ 53 cin >> n >> m >> t; 54 init(); 55 int u, v, w; 56 for(int i = 0; i < m; i++) { 57 cin >> u >> v >> w; 58 addedge(u, v, w); 59 } 60 solve(); 61 return 0; 62 }
1 #include <iostream> 2 #include <string.h> 3 using namespace std; 4 const int maxn = 5005; 5 int u[maxn], v[maxn], w[maxn], dp[maxn][maxn], parent[maxn][maxn], x[maxn]; 6 int main(){ 7 int n, m, t, pos; 8 cin >> n >> m >> t; 9 for(int i = 0; i < m; i ++){ 10 cin >> u[i] >> v[i] >> w[i]; 11 } 12 memset(dp, 0x3f, sizeof(dp)); 13 dp[1][1] = 0; 14 for(int i = 2; i <= n; i ++){ 15 for(int j = 0; j < m; j ++){ 16 if(dp[i-1][u[j]] + w[j] < dp[i][v[j]]){ 17 dp[i][v[j]] = dp[i-1][u[j]] + w[j]; 18 parent[i][v[j]] = u[j]; 19 } 20 } 21 if(dp[i][n] <= t) pos = i; 22 } 23 int id = n; 24 for(int i = pos; i >= 1; i--){ 25 x[i] = id; 26 id = parent[i][id]; 27 } 28 cout << pos <<endl; 29 for(int i = 1; i <= pos; i ++) cout << x[i]<<" "; 30 return 0; 31 }
http://codeforces.com/contest/733/problem/D
内切球（W的爽啊）
1 #include <iostream> 2 #include <algorithm> 3 using namespace std; 4 const int maxn = 1e5+10; 5 struct Node{ 6 long long x, y, z, w; 7 }T[maxn]; 8 long long cmp(Node a, Node b){ 9 if(a.y == b.y && a.z == b.z) return a.x < b.x; 10 if(a.y == b.y) return a.z < b.z; 11 return a.y < b.y; 12 } 13 int main(){ 14 long long n, mi = -1, a[4], num, num1, num2; 15 cin >> n; 16 for(int i = 0; i < n; i++){ 17 cin >> a[0] >> a[1] >> a[2]; 18 sort(a, a+3); 19 T[i].x = a[0], T[i].y = a[1], T[i].z = a[2], T[i].w = i+1; 20 if(a[0] > mi){ 21 mi = a[0]; 22 num = i+1; 23 } 24 } 25 sort(T, T+n, cmp); 26 long long mm = -1; 27 for(int i = 1; i < n; i++){ 28 if(T[i].y == T[i-1].y && T[i].z == T[i-1].z){ 29 long long t = min(T[i].x+T[i-1].x, T[i].y); 30 if(t > mm){ 31 mm = t; 32 num1 = T[i].w, num2 = T[i-1].w; 33 } 34 } 35 } 36 if(mi >= mm) { 37 cout<<1<<endl<<num<<endl; 38 }else{ 39 cout<<2<<endl<<num1<<" "<<num2<<endl; 40 } 41 return 0; 42 }
好屌
http://codeforces.com/contest/738/problem/A
1 #include <bits/stdc++.h> 2 using namespace std; 3 4 int main() { 5 string s; cin >> s >> s; 6 cout << regex_replace(s, regex("o(go)+"), "***") << ' '; 7 return 0; 8 }
http://codeforces.com/contest/749/problem/D
投票。。。。。。
1 #include <iostream> 2 #include <stdio.h> 3 #include <vector> 4 #include <map> 5 using namespace std; 6 const int maxn = 2e5+10; 7 vector<int> v[maxn]; 8 int vv[maxn], b[maxn]; 9 map<int, int > m; 10 map<int, int > :: iterator it; 11 int main(){ 12 int n, q, x, y; 13 scanf("%d", &n); 14 for(int i = 0; i < n; i++){ 15 scanf("%d%d", &x, &y); 16 v[x].push_back(y); 17 vv[x] = y; 18 } 19 m[0] = 0; 20 for(int i = 1; i <= n; i++){ 21 if(vv[x]){ 22 m[vv[i]] = i; 23 } 24 } 25 scanf("%d", &q); 26 while(q--){ 27 int x, xx; 28 scanf("%d", &x); 29 for(int i = 0; i < x; i++){ 30 scanf("%d", &xx); 31 b[i] = xx; 32 if(vv[xx]) m.erase(vv[xx]); 33 } 34 it = m.end(); 35 it --; 36 if(it == m.begin()){ 37 printf("0 0 "); 38 }else{ 39 int itt = it->second; 40 it--; 41 printf("%d %d ", itt, *lower_bound(v[itt].begin(), v[itt].end(), it->first)); 42 } 43 for(int i = 0; i < x; i++){ 44 if(vv[b[i]]) m[vv[b[i]]] = b[i]; 45 } 46 } 47 return 0; 48 }
http://codeforces.com/contest/752/problem/C
圣诞老人送礼物
上下左右四个点中三个点就可以确定一个点；；fuck
1 #include <bits/stdc++.h> 2 using namespace std; 3 map<char, int> m; 4 int main(){ 5 int n, sum = 1; 6 string str; 7 cin >> n >> str; 8 for(int i = 0; i < n; i++){ 9 m[str[i]] ++; 10 if((m['L'] > 0&& m['R'] > 0) ||(m['U'] > 0 && m['D'] > 0)){ 11 sum ++; 12 m['L'] = 0, m['R'] = 0, m['U'] = 0, m['D'] = 0; 13 m[str[i]] ++; 14 } 15 } 16 printf("%d ", sum); 17 return 0; 18 }
大神就是这样出神入化
1 #include<cstdio> 2 #include<cstring> 3 char s[200010]; 4 bool b[10]; 5 int d[1000]; 6 int main() 7 { 8 int n,i,ans; 9 scanf("%d%s",&n,s+1); 10 ans=0; 11 d['L'-'A'+1]=0; 12 d['U'-'A'+1]=1; 13 d['D'-'A'+1]=2; 14 d['R'-'A'+1]=3; 15 for (i=1;i<=n;i++) 16 { 17 if (b[3-d[s[i]-'A'+1]]) 18 { 19 ans++; 20 b[0]=b[1]=b[2]=b[3]=0; 21 } 22 b[d[s[i]-'A'+1]]=1; 23 } 24 printf("%d ",ans+1); 25 }
http://codeforces.com/contest/750/problem/A
自己太菜。。。。。别人可以一分钟就秒的题硬是做了二十多分钟。。。。垃圾。。。
自己的代码：
1 #include <bits/stdc++.h> 2 using namespace std; 3 int main(){ 4 int n, m, sum = 0, a = 5; 5 scanf("%d%d", &n, &m); 6 m = 240 - m; 7 if((10+(n-1)*5)*n/2 < m){ 8 printf("%d ", n); 9 return 0; 10 } 11 for(int i = 0; ; i++){ 12 if(sum == m){ 13 printf("%d ", i); 14 return 0; 15 } 16 if(sum > m){ 17 printf("%d ", i-1); 18 return 0; 19 } 20 sum += a; 21 a+=5; 22 } 23 return 0; 24 }
大大神代码：
1 #include <stdio.h> 2 #include <iostream> 3 using namespace std; 4 int main(){ 5 int n, m, num = 0; 6 scanf("%d %d", &n, &m); 7 for(int i = 1; i <= n; i++){ 8 if(m+5*i <= 240){ 9 num ++; 10 m += 5*i; 11 } 12 } 13 printf("%d ", num); 14 }
模拟。。。什么是模拟，。。，，。，。，按照实际的思路写（当你面对的时候会怎么办）
http://codeforces.com/contest/750/problem/C
菜如狗
cf排名
1 #include <bits/stdc++.h> 2 using namespace std; 3 const int maxn = 0x3f3f3f3f; 4 int main(){ 5 int n, a = maxn, b = -maxn, sum = 0, m , t; 6 scanf("%d", &n); 7 for(int i = 0; i < n; i++){ 8 scanf("%d %d", &m, &t); 9 if(t == 1){ 10 a = min(a, sum); 11 }else{ 12 b = max(b, sum); 13 } 14 sum += m; 15 } 16 if(a <= b){ 17 puts("Impossible"); 18 return 0; 19 } 20 if(b == -maxn){ 21 puts("Infinity"); 22 return 0; 23 } 24 printf("%d ", 1899 - b + sum); 25 return 0; 26 }
只有不断学习才能进步！