网络最大流EK算法

#include <iostream>
#include <queue>
using namespace std;

const int maxn = 220;
const int inf = INT_MAX;
int G[maxn][maxn], flow[maxn], pre[maxn];
int n, m;
queue <int> q;

int bfs(int s, int t) {
	while (!q.empty()) q.pop();
	memset(pre, -1, sizeof(pre));
	pre[s] = 0, flow[s] = inf;
	q.push(s);
	while (!q.empty()) {
		int p = q.front(); q.pop();
		if (p == t)break;
		for (int u = 1; u <= n; u++) {
			if (u != s && G[p][u] > 0 && pre[u] == -1) {
				pre[u] = p;
				flow[u] = min(flow[p], G[p][u]);
				q.push(u);
			}
		}
	}
	if (pre[t] == -1)return -1;
	return flow[t];
}

int EK(int s,int t) {
	int delta = 0, tot = 0;
	while (true) {
		delta = bfs(s, t);
		if (delta == -1) break;
		int p = t;
		while (p != s) {
			G[pre[p]][p] -= delta;
			G[p][pre[p]] += delta;
			p = pre[p];
		}
		tot += delta;
	}
	return tot;
}

int main() {
	cin >> m >> n;
	int u, v, w;
	memset(G, 0, sizeof(G));
	memset(flow, 0, sizeof(flow));
	for (int i = 0; i < m; i++) {
		cin >> u >> v >> w;
		G[u][v] += w;
	}
	cout << EK(1, n) << endl;
	return 0;
}