网络流入门 Drainage Ditches

#include<iostream>
#include<cstdio>
#include<cmath>
#include<cstring>
#include<sstream>
#include<algorithm>
#include<queue>
#include<deque>
#include<iomanip>
#include<vector>
#include<cmath>
#include<map>
#include<stack>
#include<set>
#include<fstream>
#include<memory>
#include<list>
#include<string>
using namespace std;
typedef long long LL;
typedef unsigned long long ULL;
#define MAXN  1100
#define L 31
#define INF 1000000009
#define eps 0.00000001
/*
最大流问题
*/
int g[MAXN][MAXN], path[MAXN], flow[MAXN], start, End, n, m;
int bfs()
{
    queue<int> q;
    q.push(start);
    memset(path, -1, sizeof(path));
    path[start] = 0;
    flow[start] = INF;
    while (!q.empty())
    {
        int tmp = q.front();
        q.pop();
        if (tmp == End) break;
        for (int i = 1; i <= n; i++)
        {
            if (i != start&&g[tmp][i] && path[i] == -1)
            {
                flow[i] = min(g[tmp][i], flow[tmp]);
                path[i] = tmp;
                q.push(i);
            }
        }
    }
    if (path[End] == -1) return -1;
    return flow[End];
}
int EK()
{
    int max_flow = 0, now, step;
    while ((step = bfs())!= -1)
    {
        max_flow += step;
        now = End;
        while (now != start)
        {
            int pre = path[now];
            g[pre][now] -= step;
            g[now][pre] += step;
            now = pre;
        }
    }
    return max_flow;
}
int main()
{
    while (scanf("%d%d", &m, &n) != EOF)
    {
        memset(g, 0, sizeof(g));
        int f, t, d;
        for (int i = 0; i < m; i++)
        {
            scanf("%d%d%d", &f, &t, &d);
            g[f][t] += d;
        }
        start = 1, End = n;
        printf("%d\n", EK());
    }
}