Dinic 模板

#include <iostream>
#include <cstring>
#include <cstdio>
#include <queue>

using namespace std;
const int INF=2147483647;
const int maxn=210,maxm=410;
int cnt,fir[maxn],nxt[maxm],cap[maxm],to[maxm],dis[maxn];

void addedge(int a,int b,int c)
{
    nxt[++cnt]=fir[a];
    to[cnt]=b;
    cap[cnt]=c;
    fir[a]=cnt;
}

bool BFS(int S,int T)
{
    memset(dis,0,sizeof(dis));
    dis[S]=1;
    queue<int>q;q.push(S);
    while(!q.empty())
    {
        int node=q.front();q.pop();
        for(int i=fir[node];i;i=nxt[i])
        {
            if(!cap[i]||dis[to[i]])continue;
            dis[to[i]]=dis[node]+1;
            q.push(to[i]);
        }
    }
    return dis[T];
}

int DFS(int node,int T,int f)
{
    if(node==T)return f; 
    int d,ret=0;
    for(int i=fir[node];i;i=nxt[i])
    {
        if(!cap[i]||dis[to[i]]!=dis[node]+1)continue;
        if(!f)break;
        d=DFS(to[i],T,min(cap[i],f));
        if(d){
            ret+=d;
            cap[i]-=d;
            cap[i^1]+=d;
            f-=d;
        }
    }
    return ret;
}

int Dinic(int S,int T)
{
    int ret=0,d;
    while(BFS(S,T)&&(d=DFS(S,T,INF)))
        ret+=d;
    return ret;    
}

void Init()
{
    memset(fir,0,sizeof(fir));
    cnt=1;
}
int main()
{
    int n,m;
    while(~scanf("%d%d",&m,&n))
    {
        Init();
        for(int i=1;i<=m;i++){
            int x,y,c;
            scanf("%d%d%d",&x,&y,&c);
            addedge(x,y,c);
            addedge(y,x,0);
        }
        printf("%d
",Dinic(1,n));
    }

    return 0;
}