HDU 3549 Flow Problem（最大流模板）

http://acm.hdu.edu.cn/showproblem.php?pid=3549

刚接触网络流，感觉有点难啊，只好先拿几道基础的模板题来练练手。

最大流的模板题。

 #include<iostream>
 #include<cstring>
 #include<string>
 #include<algorithm>
 #include<queue>
 using namespace std;

 int n, m, flow;
 int vis[];
 //路径记录
 int pre[];
 //邻接表
 int G[][];

 void Maxflow()
 {
     for (;;)
     {
         memset(vis, , sizeof(vis));
         memset(pre, , sizeof(pre));
         queue<int> q;
         q.push();
         vis[] = ;
         while (!q.empty())
         {
             int x = q.front();
             q.pop();
             //到达终点
             if (x == n)  break;
             for (int i = ; i <= n; i++)
             {
                 if (!vis[i] && G[x][i] > )
                 {
                     vis[i] = ;
                     q.push(i);
                     //记录好路径
                     pre[i] = x;
                 }
             }
         }
         //没有找到增广路
         if (!vis[n])  break;
         int _min = ;
         for (int i = n; i != ; i = pre[i])
             _min = min(_min, G[pre[i]][i]);
         for (int i = n; i != ; i = pre[i])
         {
             G[i][pre[i]] += _min;
             G[pre[i]][i] -= _min;
         }
         flow += _min;
     }
     return;
 }

 int main()
 {
     //freopen("D:\\txt.txt", "r", stdin);
     int T;
     int u, v, w;
     cin >> T;
     for (int kase = ; kase <= T; kase++)
     {
         cin >> n >> m;
         memset(G, , sizeof(G));
         for (int i = ; i < m; i++)
         {
             cin >> u >> v >> w;
             G[u][v] += w;
         }
         flow = ;
         Maxflow();
         cout << "Case " << kase << ": " << flow << endl;
     }
 }