rt，如果是数据改过说下

看到 EK 跑的都比我这个快，很是不解。

明早来看。

836ms

#include <bits/stdc++.h>
#define int long long
using namespace std;

const int N = 205, M = 5005;
int n, m, s, t, maxflow;
int dep[N], flow[M << 1];
struct edge
{
	int to, nxt;
}e[M << 1];
int head[N], idx = 1;
void add(int x, int y, int w) {e[ ++ idx] = {y, head[x]}, head[x] = idx, flow[idx] = w;}

bool bfs()
{
	queue<int> q;
	memset(dep, 0, sizeof dep);
	q.push(s), dep[s] = 1;
	while (!q.empty())
	{
		int u = q.front(); q.pop();
		for (int i = head[u]; i; i = e[i].nxt)
		{
			int v = e[i].to;
			if (flow[i] && !dep[v])
			{
				dep[v] = dep[u] + 1;
				q.push(v);
			}
		}
	}
	return dep[t];
}
int dfs(int u, int in)
{
	if (u == t) return in;
	int out = 0;
	for (int i = head[u]; i; i = e[i].nxt)
	{
		int v = e[i].to;
		if (flow[i] && dep[v] == dep[u] + 1)
		{
			int fl = dfs(v, min(flow[i], in));
			flow[i] -= fl, flow[i ^ 1] += fl;
			in -= fl, out += fl;
		}
	}
	if (!out) dep[u] = 0;
	return out;
}

signed main()
{
	scanf("%lld%lld%lld%lld", &n, &m, &s, &t);
	for (int i = 1, x, y, w; i <= m; i ++ )
		scanf("%lld%lld%lld", &x, &y, &w), add(x, y, w), add(y, x, 0);
	while (bfs()) maxflow += dfs(s, 1e18);
	printf("%lld\n", maxflow);
	return 0;
}