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EK 求最大流

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#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 1005, M = 20005,INF=1e8;
int n, m, S, T;
int h[N], e[M], f[M], ne[M], idx;
int q[N], d[N], pre[N];
bool st[N];
void add(int a,int b,int c){e[idx] = b, f[idx] = c, ne[idx] = h[a], h[a] = idx++;e[idx] = a, f[idx] = 0, ne[idx] = h[b], h[b] = idx++;
}bool bfs(){int hh = 0, tt = 0;memset(st, 0, sizeof(st));q[0] = S, st[S] = 1,d[S] = INF;while(hh<=tt){int t = q[hh++];for (int i = h[t]; ~i;i=ne[i]){int ver = e[i];if(!st[ver]&&f[i]){st[ver] = 1;d[ver] = min(d[t], f[i]);pre[ver] = i;if(ver==T) return 1;q[++tt] = ver;}}}return 0;
}
int EK(){int r = 0; while(bfs()){r += d[T];for (int i = T; i != S;i=e[pre[i]^1])f[pre[i]] -= d[T], f[pre[i]^1] += d[T];}return r;
}
int main(){memset(h, -1, sizeof(h));cin >> n >> m >> S >> T;while(m--){int a, b, c;cin >> a >> b >> c;add(a, b, c);}cout << EK() << endl;return 0;
}