hdu 3549 Flow Problem（最大流，Edmond Karp）

和1532题一样的套路

#include <iostream>
#include <queue>
#include <cstring>
#include <algorithm>
#define INF 99999999
#define len 1005
using namespace std;
int r[len][len];
int pre[len];
bool vis[len];
int N,M;
bool BFS(int s, int t)
{
    memset(pre,-1,sizeof(pre));
    memset(vis,false,sizeof(vis));
    queue<int> que;
    que.push(s);
    pre[s] = s;
    vis[s] = true;
    int p;
    while(!que.empty())
    {
        p = que.front();
        que.pop();
        for(int i = 1; i <= M; ++i)
        {
            if(r[p][i] > 0 && !vis[i])
            {
                pre[i] = p;
                vis[i] = true;
                if(i == t)
                    return true;
                que.push(i);
            }
        }
    }
    return false;
}

int EK(int s, int t)
{
    int maxflow = 0,d;
    while(BFS(s,t))
    {
        d = INF;
        for(int i = t; i != s; i = pre[i])
            d = min(d,r[pre[i]][i]);
        for(int i = t; i != s; i = pre[i])
        {
            r[pre[i]][i] -= d;
            r[i][pre[i]] += d;
        }
        maxflow += d;
    }
    return maxflow;
}

int main()
{
    int T,time;
    cin >> T;
    while(T--)
    {
        time = 1;
        while(cin >> M >> N)
        {
            memset(r,0,sizeof(r));
            int s,e,c;
            for(int i = 0; i < N; ++i)
            {
                cin >> s >> e >> c;
                r[s][e] += c;
            }
            cout << "Case " << time << ": " << EK(1,M) << endl;
            ++time;
        }
    }
    return 0;
}