【模板】网络最大流

题目链接

        Dinic算法，模板题，无题解。

Code：

#include<bits/stdc++.h>
#define rep(i,j,k) for(int i=j;i<=k;i++)
#define inf INT_MAX
using namespace std;
template<typename T> void read(T &num){
	char c=getchar();num=0;T f=1;
	while(c<'0'||c>'9'){if(c=='-')f=-1;c=getchar();}
	while(c>='0'&&c<='9'){num=(num<<3)+(num<<1)+(c^48);c=getchar();}
	num*=f;
}
template<typename T> void qwq(T x){
	if(x>9)qwq(x/10);
	putchar(x%10+'0');
}
template<typename T> void write(T x){
	if(x<0){x=-x;putchar('-');}
	qwq(x);putchar('\n');
}
int s,t;
struct wzy{
	int nxt,vertice,w;
}edge[200010];
int head[10010];int len=1;
inline void add_edge(int x,int y,int z){
	edge[++len].nxt=head[x];edge[len].vertice=y;
	edge[len].w=z;head[x]=len;return;
}

int d[10010];queue<int>v;
inline bool bfs(){
	memset(d,0,sizeof(d));
	while(!v.empty())v.pop();
	v.push(s);d[s]=1;
	while(!v.empty()){
		int nop=v.front();v.pop();
		for(int i=head[nop];i;i=edge[i].nxt){
			int temp=edge[i].vertice;
			if(edge[i].w&&!d[temp]){
				v.push(temp);d[temp]=d[nop]+1;
				if(temp==t)return 1;
			}
		}
	}
	return 0;
}
inline int dinic(int now,int val){
	if(now==t)return val;
	int k=0;
	for(int i=head[now];i&&k!=val;i=edge[i].nxt){
		int nop=edge[i].vertice;
		if(!edge[i].w||d[nop]!=d[now]+1)continue;
		int temp=dinic(nop,min(val-k,edge[i].w));
		if(!temp)d[nop]=0;
		edge[i].w-=temp;edge[(i^1)].w+=temp;k+=temp;
	}
	return k;
}

int main(){
	int n,m;read(n);read(m);read(s);read(t);
	rep(i,1,m){
		int u,v,c;read(u);read(v);read(c);
		add_edge(u,v,c);add_edge(v,u,0);
	}
	
	long long max_flow=0;int flow;
	while(bfs()){
		do{
			flow=dinic(s,inf);max_flow+=flow;
		}while(flow);
	}
	write(max_flow);
	return 0;
}