hdu 3549 Flow Problem【最大流】

直接模板

#include<iostream>
using namespace std;
const int maxn=20;
const int inf=0x3f3f3f3f;

struct EK
{
    int cap[maxn][maxn];
    int flow[maxn][maxn];
    int n;
    void init(int n)
    {
        this->n=n;
        memset(cap,0,sizeof(cap));
    }
    void addcap(int i,int j,int val)
    {
        cap[i][j]+=val;
    }
    int solve(int source,int sink)
    {
        if(source==sink) return inf;
        static int que[maxn],pre[maxn],d[maxn];
        int p,q,t;
        memset(flow,0,sizeof(flow));
        while(1)
        {
            memset(pre,255,sizeof(pre));
            d[source]=inf;
            p=q=0;
            que[q++]=source;
            while(p<q&&pre[sink]==-1)
            {
                t=que[p++];
                for(int i=0;i<n;i++)
                {
                    if(pre[i]==-1&&cap[t][i]-flow[t][i]>0)
                    {
                        pre[i]=t;
                        que[q++]=i;
                        d[i]=min(d[t],cap[t][i]-flow[t][i]);
                    }
                }
            }
            if(pre[sink]==-1) break;
            for(int i=sink;i!=source;i=pre[i])
            {
                flow[pre[i]][i]+=d[sink];
                flow[i][pre[i]]-=d[sink];
            }
        }
        t=0;
        for(int i=0;i<n;i++)
            t+=flow[source][i];
        return t;
    }
}ek;
int main()
{
    int t,n,m,cas=1;
    cin>>t;
    while (t--) {
        cin>>n>>m;
        ek.init(n+1);
        int a,b,c;
        for(int i=0;i<m;i++)
        {
            cin>>a>>b>>c;
            ek.addcap(a,b,c);
        }
        cout<<"Case "<<cas++<<": ";
        cout<<ek.solve(1, n)<<endl;
    }
    return 0;
}