hdu 3549 Flow Problem 【最大流】

其实还是不是很懂dinic-----

抄了一个模板---

http://www.cnblogs.com/naturepengchen/articles/4403408.html

先放在这里～～～

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

const int maxn = 10005;
const int INF = (1 << 30) - 1;

struct Edge{
    int v,next,c;
}e[maxn];

int st,ed,lev[maxn],first[maxn],now[maxn],ecnt;
int n,m;

void init(int a,int b){
    st = a; ed = b;
    memset(first,-1,sizeof(first));
    ecnt = 0;
}

void addedges(int u,int v,int c){
    e[ecnt].next = first[u];
    e[ecnt].v = v;
    e[ecnt].c = c;
    first[u] = ecnt++;
    
    e[ecnt].next = first[v];
    e[ecnt].v = u;
    e[ecnt].c = 0;
    first[v] = ecnt++;
}

bool bfs(){
    queue<int> q;
    while(!q.empty()) q.pop();
    q.push(st);
    memset(lev,-1,sizeof(lev));
    lev[st] = 0;
    while(!q.empty()){
        int x = q.front();q.pop();
        for(int i = first[x];~i;i = e[i].next){
            int v = e[i].v;
            if(lev[v] < 0 && e[i].c > 0){
                lev[v] = lev[x] + 1;
                q.push(v);
            }
        }
    }
    return lev[ed] != -1;
}

int dfs(int p,int minf){
    if(p == ed || minf == 0) return minf;
    for(int &i = now[p];~i;i = e[i].next){
        int v = e[i].v;
        if(lev[v] == lev[p] + 1 && e[i].c > 0){
            int d = dfs(v,min(e[i].c,minf));
            if(d > 0){
                e[i].c -= d;
                e[i^1].c += d;
                return d;
            }
        }
    }
    return 0;
}

int dinic(){
    int max_flow = 0,p1;
    while(bfs()){
        memcpy(now,first,sizeof(first));
        while((p1 = dfs(st,INF)) > 0)
        max_flow += p1;
    }
    return max_flow;
}

int main(){
    int T;
    int kase = 0;
    scanf("%d",&T);
    while(T--){        
        scanf("%d %d",&n,&m);
        init(1,n);
        for(int i = 0;i < m;i++){
            int a,b,c;
            scanf("%d %d %d",&a,&b,&c);
            addedges(a,b,c);
        }
        printf("Case %d: %d
",++kase,dinic());
    }
    return 0;
}