图论--网络流--费用流--POJ 2156 Minimum Cost

1 3 3   
1 1 1
0 1 1
1 2 2
1 0 1
1 2 3
1 1 1
2 1 1

1 1 1
3
2
20

0 0 0
Sample Output
4
-1

#include<cstdio>
#include<cstring>
#include<queue>
#include<algorithm>
#include<vector>
#define INF 1e9
using namespace std;
const int maxn=200+10;
 
struct Edge
{
    int from,to,cap,flow,cost;
    Edge(){}
    Edge(int f,int t,int c,int fl,int co):from(f),to(t),cap(c),flow(fl),cost(co){}
};
 
struct MCMF
{
    int n,m,s,t;
    vector<Edge> edges;
    vector<int> G[maxn];
    bool inq[maxn];
    int d[maxn];
    int p[maxn];
    int a[maxn];
 
    void init(int n,int s,int t)
    {
        this->n=n, this->s=s, this->t=t;
        edges.clear();
        for(int i=0;i<n;++i) G[i].clear();
    }
 
    void AddEdge(int from,int to,int cap,int cost)
    {
        edges.push_back(Edge(from,to,cap,0,cost));
        edges.push_back(Edge(to,from,0,0,-cost));
        m=edges.size();
        G[from].push_back(m-2);
        G[to].push_back(m-1);
    }
 
    bool BellmanFord(int &flow, int &cost)
    {
        for(int i=0;i<n;++i) d[i]=INF;
        memset(inq,0,sizeof(inq));
        d[s]=0, a[s]=INF, inq[s]=true, p[s]=0;
        queue<int> Q;
        Q.push(s);
        while(!Q.empty())
        {
            int u=Q.front(); Q.pop();
            inq[u]=false;
            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]=true; }
                }
            }
        }
        if(d[t]==INF) return false;
        flow +=a[t];
        cost +=a[t]*d[t];
        int u=t;
        while(u!=s)
        {
            edges[p[u]].flow += a[t];
            edges[p[u]^1].flow -=a[t];
            u = edges[p[u]].from;
        }
        return true;
    }
    int Min_cost()
    {
        int flow=0,cost=0;
        while(BellmanFord(flow,cost));
        return cost;
    }
}MM;
 
int n,m,k;
int need[50+5][50+5];       //need[i][j]表i顾客对j商品的需求量
int have[50+5][50+5];       //have[i][j]表i仓库对j商品的提供量
int cost[50+5][50+5][50+5]; //cost[x][i][j] 表j仓库到i顾客对x商品的单位运费
 
int main()
{
    while(scanf("%d%d%d",&n,&m,&k)==3 && n)
    {
        int goods[maxn];//货物需求量,用来判断货物是否足够
        int enough=true;//初始货物充足
        memset(goods,0,sizeof(goods));
 
        for(int i=1;i<=n;++i)
        for(int j=1;j<=k;++j)
        {
            scanf("%d",&need[i][j]);
            goods[j]+= need[i][j];
        }
 
        for(int i=1;i<=m;++i)
        for(int j=1;j<=k;++j)
        {
            scanf("%d",&have[i][j]);
            goods[j] -=have[i][j];
        }
 
        for(int h=1;h<=k;++h)
        for(int i=1;i<=n;++i)
        for(int j=1;j<=m;++j)
            scanf("%d",&cost[h][i][j]);
 
        for(int i=1;i<=k;++i)if(goods[i]>0)//货物不足,不用计算了
        {
            enough=false;
            break;
        }
        if(!enough)//初始货物不足
        {
            printf("-1\n");
            continue;
        }
 
        int min_cost=0;
        for(int g=1;g<=k;++g)
        {
            int src=0, dst=n+m+1;
            MM.init(n+m+2,src,dst);
            for(int i=1;i<=m;++i) MM.AddEdge(src,i,have[i][g],0);
            for(int i=1;i<=n;++i) MM.AddEdge(m+i,dst,need[i][g],0);
            for(int i=1;i<=m;++i)
            for(int j=1;j<=n;++j)
            {
                MM.AddEdge(i,j+m,INF,cost[g][j][i]);
            }
            min_cost += MM.Min_cost();
        }
        printf("%d\n",min_cost);
    }
    return 0;
}