【模板】最小费用最大流

仅仅是个模板

(Code)

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

const int M = 50000 , N = 5000;
int n , m , s , t , dis[N + 5] , h[N + 5] , vis[N + 5] , pre[N + 5] , edge[N + 5] , flow[N + 5] , tot = 1 , Maxflow , Mincost;

queue<int> d;
struct node{
	int to , nxt , w , f;
}e[M << 1 + 10];

void add(int u , int v , int w , int f)
{
	e[++tot].to = v;
	e[tot].w = w;
	e[tot].f = f;
	e[tot].nxt = h[u];
	h[u] = tot;
}

int spfa()
{
	memset(vis , 0 , sizeof(vis));
	memset(dis , 127 , sizeof(dis));
	memset(flow , 127 , sizeof(flow));
	d.push(s);
	vis[s] = 1 , dis[s] = 0 , pre[t] = -1;
	while (!d.empty())
	{
		int now = d.front();
		d.pop();
		vis[now] = 0;
		for(register int i = h[now]; i; i = e[i].nxt)
		{
			if (dis[e[i].to] > dis[now] + e[i].f && e[i].w)
			{
				dis[e[i].to] = dis[now] + e[i].f;
				flow[e[i].to] = min(flow[now] , e[i].w);
				pre[e[i].to] = now;
				edge[e[i].to] = i;
				if (!vis[e[i].to]) vis[e[i].to] = 1 , d.push(e[i].to);
			} 
		}
	}
	return (pre[t] != -1);
}

int MCMF()
{
	while (spfa()) 
	{
		Maxflow += flow[t];
		Mincost += dis[t] * flow[t];
		int now = t;
		while (now != s)
		{
			e[edge[now]].w -= flow[t];
			e[edge[now] ^ 1].w += flow[t];
			now = pre[now];
		}
	}
}

int main()
{
	scanf("%d%d%d%d" , &n , &m , &s , &t);
	int u , v , w , f;
	for(register int i = 1; i <= m; i++) scanf("%d%d%d%d" , &u , &v , &w , &f) , add(u , v , w , f) , add(v , u , 0 , -f);
	MCMF();
	printf("%d %d" , Maxflow , Mincost);
}