dinic网络流模板

src：源点

sink：汇点

#include<queue>
#include<iostream>
#include<string.h>
#include<stdio.h>
using namespace std;

const int inf = 1000000000;
const int maxn = 20000, maxm = 500000;
struct Edge{
    int v, f, nxt;
};
int src, sink;
int g[maxn + 10];
int nume;
Edge e[maxm*2+10];
void addedge(int u, int v, int c){
    e[++nume].v = v;
    e[nume].f = c;
    e[nume].nxt = g[u];
    g[u] = nume;
    e[++nume].v = u;
    e[nume].f = 0;
    e[nume].nxt = g[v];
    g[v] = nume;
}
void init(){
    memset(g, 0, sizeof(g));
    nume = 1;
}
queue<int> que;
bool vis[maxn +10];
int dist[maxn + 10];
void bfs(){
    memset(dist, 0, sizeof(dist));
    while(!que.empty()) que.pop();
    vis[src] = 1;
    que.push(src);
    while(!que.empty()){
        int u = que.front();
        que.pop();
        for(int i = g[u]; i; i = e[i].nxt)
            if(e[i].f && !vis[e[i].v]){
                que.push(e[i].v);
                dist[e[i].v] = dist[u] + 1;
                vis[e[i].v] = true;
            }
    }
}
int dfs(int u, int delta){
    if(u == sink){
        return delta;
    }else{
        int ret = 0;
        for(int i = g[u]; delta && i; i = e[i].nxt){
            if(e[i].f && dist[e[i].v] == dist[u] +1){
                int dd = dfs(e[i].v, min(e[i].f, delta));
                e[i].f -= dd;
                e[i^1].f += dd;
                delta -= dd;
                ret += dd;
            }
        }
        return ret;
    }
}
int maxflow(){
    int ret = 0;
    while(true){
        memset(vis, 0, sizeof(vis));
        bfs();
        if(!vis[sink])return ret;
        ret += dfs(src, inf);
    }
    return ret;
}
int main(){
    int n, m;
    while(scanf("%d%d", &n, &m)!=EOF){
        init();
        src = 1;
        sink = m;
        for(int i = 0; i < n; i++){
            int x, y, z;
            scanf("%d%d%d", &x, &y, &z);
            addedge(x, y, z);
        }
        printf("%d
", maxflow());
    }
}