网络最大流模板(Dinic算法)

测试模板能不能过的——————题目链接

#include <bits/stdc++.h>
const int maxn = 10050;
const int inf = 0x3f3f3f3f;
using namespace std;
typedef long long ll;
struct note{
    int u, v, w;
    int next;
}e[maxn*20];
int head[maxn], cnt;
int level[maxn];
int n, m, s, t;

void add(int u, int v, int w){
    e[cnt].u = u, e[cnt].v = v, e[cnt].w = w;
    e[cnt].next = head[u], head[u] = cnt++;

    e[cnt].u = v, e[cnt].v = u, e[cnt].w = 0;
    e[cnt].next = head[v], head[v] = cnt++;
}

bool bfs(){
    queue <int> q;
    memset(level, -1, sizeof(level));
    level[s] = 0;
    q.push(s);
    while(!q.empty()){
        int u = q.front();
        q.pop();
        for(int i=head[u]; ~i; i=e[i].next){
            int v = e[i].v;
            if(e[i].w > 0 && level[v]==-1){
                level[v] = level[u]+1;
                q.push(v);
            }
        }
    }
    return level[t] != -1;
}

int dfs(int u, int delta){
    if(u == t)
        return delta;
    int flow = 0;
    for(int i=head[u]; ~i; i=e[i].next){
        int v = e[i].v;
        if(e[i].w > 0 && level[u] + 1 == level[v]){
            int tmp = dfs(v, min(delta-flow, e[i].w));
            e[i].w -= tmp;
            e[i^1].w += tmp;
            flow += tmp;
        }
    }
    if(!flow)
        level[u] = inf;
    return flow;
}

void Dinic()
{
    int maxflow = 0, tmp;
    while(bfs()){
        while((tmp = dfs(s, inf)))
            maxflow += tmp;
    }
    printf("%d
", maxflow);
}

int main()
{
    while(scanf("%d%d%d%d", &n, &m, &s, &t)!=EOF){
        for(int i=0; i<=n; i++)
            head[i] = -1;
        for(int i=0; i<m; i++){
            int a, b, w;
            scanf("%d%d%d", &a, &b, &w);
            add(a, b, w);
        }
        Dinic();
    }
    return 0;
}