hdu1532 Drainage Ditches--最大流ek

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原题链接： http://acm.hdu.edu.cn/showproblem.php?pid=1532

题意：

n条路，m个点，每条边一个流速，求最大流速，1是源点，m是汇点。

依旧模板题。

#define _CRT_SECURE_NO_DEPRECATE #include<cstdio>#include<cstring>#include<iostream>#include<algorithm>#include<cmath>#include<queue>using namespace std;int n, m;int s, t;int pre[205];int vis[205];int p[205][205];bool bfs(){memset(pre, 0, sizeof(pre));memset(vis, 0, sizeof(vis));vis[s] = 1;queue<int> Q;Q.push(s);while (!Q.empty()){int cur = Q.front();Q.pop();if (cur == t)return true;for (int i = 1; i <= n; i++){if (!vis[i] && p[cur][i]){pre[i] = cur;vis[i] = 1;Q.push(i);}}}return false;}int maxFlow(){int ans = 0;while (1){if (!bfs())return ans;int minn = 99999999;for (int i = t; i != s; i = pre[i])minn = min(minn, p[pre[i]][i]);for (int i = t; i != s; i = pre[i]){p[pre[i]][i] -= minn;p[i][pre[i]] += minn;}ans += minn;}}int main(){int u, v, w;while (~scanf("%d%d", &m, &n)){s = 1;t = n;memset(p, 0, sizeof(p));//注意这里要初始化for (int i = 1; i <= m; i++){scanf("%d%d%d", &u, &v, &w);p[u][v] += w;}printf("%d\n", maxFlow());}return 0;}

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