UVa(12821)，MCMF

#include <iostream>
#include <stdio.h>
#include <cstring>
#include <vector>
#include <queue>
#define INF 0x3f3f3f3f
using namespace std;
const int maxn = 600;
struct Edge
{
    int from,to,cap,flow,cost;
    Edge() {}
    Edge(int a,int b,int c,int d,int e):from(a),to(b),cap(c),flow(d),cost(e) {}
};
struct MCMF
{
    int n,m,s,t;
    vector<Edge> edges;
    vector<int> g[maxn];
    int inq[maxn];
    int d[maxn];
    int p[maxn];
    int a[maxn];

    void init(int n)
    {
        this->n =n;
        for(int i=0; i<n; i++)g[i].clear();
        edges.clear();
    }
    void addedge(int from,int to,int cap,int cost)
    {
        Edge e1= Edge(from,to,cap,0,cost), e2= Edge(to,from,0,0,-cost);
        edges.push_back(e1);
        edges.push_back(e2);
        m=edges.size();
        g[from].push_back(m-2);
        g[to].push_back(m-1);
    }
    bool spfa(int s,int t, int & flow,int & cost)
    {
        for(int i=0; i<n; i++)
            d[i]=INF;
        memset(inq,0,sizeof(inq));
        d[s]=0;
        inq[s]=1;
        p[s]=0;
        a[s]=INF;
        queue<int>q;
        q.push(s);
        while(!q.empty())
        {
            int u=q.front();
            q.pop();
            inq[u]=0;
            for(int i=0; i<g[u].size(); i++)
            {
                Edge & e = edges[g[u][i]];
                if(e.cap>e.flow && d[e.to]>d[u]+e.cost)
                {
                    d[e.to]=d[u]+e.cost;
                    p[e.to]=g[u][i];
                    a[e.to]=min(a[u],e.cap-e.flow);
                    if(!inq[e.to])
                    {
                        q.push(e.to);
                        inq[e.to]=1;
                    }
                }
            }
        }
        if(d[t]==INF)
            return false;
            
        flow+=a[t];
        cost+=a[t]*d[t];
        for(int u=t; u!=s; u=edges[p[u]].from)
        {
            edges[p[u]].flow +=a[t];
            edges[p[u]^1].flow-=a[t];
        }
        return true;
    }

    int  MincostMaxflow(int s,int t)
    {
        int flow=0,cost =0;
        while(spfa(s,t,flow,cost));
        return cost;
    }
} sol;

int main()
{
    freopen("input.txt","r",stdin);
    freopen("output.txt","w",stdout);
    int n,m,cas=1;
    while(scanf("%d%d",&n,&m)!=EOF)
    {
        int s=0,t=n+1;
        sol.init(n+2);
        while(m--)
        {
            int u,v,c,ad;
            scanf("%d%d%d%d",&u,&v,&c,&ad);
            sol.addedge(u,v,1,c);
            sol.addedge(u,v,1,c+ad);
        }
        sol.addedge(s,1,2,0);
        sol.addedge(n,t,2,0);
        printf("Case %d: %d\n",cas++,sol.MincostMaxflow(s,t));
    }
}