代码临时存放

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

const int inf = 0x3f3f3f3f;
const int N = 250, M = 1e5+5;
int head[N], now[N], d[N];
int n, m, s, t, cnt = 1;
struct Edge{
	int u, v, w;
}edges[M];

void add_edge(int u, int v, int w){
	edges[++cnt] = (Edge){v, head[u], w};
	head[u] = cnt;
}

int q[N], hd, tl;
bool bfs(){
	for(int i = 1; i <= n; i++) d[i]=inf;
	d[s] = 0, now[s] = head[s];
	hd = 1, tl = 1, q[1] = s;
	while(hd <= tl){
		int u = q[hd++];
		for(int i = head[u]; i; i = edges[i].v){
			Edge e = edges[i];
			if(e.w>0 && d[e.u] == inf){
				q[++tl] = e.u;
				now[e.u] = head[e.u];
				d[e.u] = d[u] + 1;
				if(e.u == t)
					return 1;
			}
		}
	}
	return 0;
}

int dfs(int u, int sum){
	if(u == t) return sum;
	int k, flow = 0;
	for(int i = now[u]; i && sum; i = edges[i].v){
		now[u] = i; Edge e = edges[i];
		if(e.w>0 && (d[e.u] == d[u]+1)){
			k = dfs(e.u, min(sum, e.w));
			if(!k) d[e.u] = inf;
			edges[i].w -= k, sum -= k;
			edges[i^1].w += k, flow += k;
		}
	}
	return flow;
}

void init(){
	scanf("%lld%lld%lld%lld", &n, &m, &s, &t);
	for(int i = 1; i <= m; i++){
		int u, v, w;
		scanf("%lld%lld%lld", &u, &v, &w);
		add_edge(u, v, w);
		add_edge(v, u, 0);
	}
}

signed main(){
//	freopen("in.in", "r", stdin);
//	freopen("a.out", "w", stdout);

	init(); int ans = 0;
	while(bfs()) ans += dfs(s, inf);
	printf("%lld\n", ans);
	return 0;
}