poj2516——Minimum Cost

最小费用最大流！我想杀了我自己！！！BS!

漏了一句话，折磨自己两三个小时！！！

#include<iostream> #include<cstdio> #include<cstring> using namespace std; #define maxn 55 #define maxcost 9999999 int order[maxn][maxn],supply[maxn][maxn]; int cost[maxn*2][maxn*2],g[maxn*2][maxn*2],f[maxn*2][maxn*2];//费用、容量、流 int n,m,k; int source,sink; int sum,provide; int ans; int pre[maxn*2],dist[maxn*2],max_f[maxn*2],vis[maxn*2]; bool spfa(int source ,int sink) { int queue[5000],front=0,rear=0,i,j; const int num=m+n+1; memset(pre,-1,sizeof(pre)); memset(vis,0,sizeof(vis)); vis[source]=1; for(i=0;i<=num;i++) dist[i]=maxcost; dist[source]=0; queue[rear]=source; rear++; max_f[source]=maxcost; while(front!=rear) { int temp=queue[front]; front++; for(i=0;i<=num;i++) { if(((g[temp][i]-f[temp][i])>0)&&(dist[i]>(dist[temp]+cost[temp][i]))) { dist[i]=dist[temp]+cost[temp][i]; max_f[i]=(max_f[temp]<(g[temp][i]-f[temp][i])?max_f[temp]:(g[temp][i]-f[temp][i])); pre[i]=temp; if(vis[i]==0) { queue[rear]=i; rear++; vis[i]=1; } } } vis[temp]=0; } if(pre[sink]!=-1) return true; return false; } int min_max(int source ,int sink) { int sum_cost=0,sum_flow=0; memset(f,0,sizeof(f)); while(spfa(source,sink)) { int k=sink; while(pre[k]>=0) { f[pre[k]][k]+=max_f[sink]; f[k][pre[k]]=-f[pre[k]][k]; k=pre[k]; } sum_cost+=dist[sink]*max_f[sink]; } return sum_cost; } int main() { int i,j,t; while(1) { cin>>n>>m>>k; ans=0; source=0;sink=n+m+1; bool flag=true; if(n==0&&m==0&&k==0) break; for(i=1;i<=n;i++) for(j=1;j<=k;j++) cin>>order[i][j]; for(i=1;i<=m;i++) for(j=1;j<=k;j++) cin>>supply[i][j]; for(t=1;t<=k;t++) { sum=0;provide=0; memset(cost,0,sizeof(cost)); for(i=1;i<=n;i++) for(j=1;j<=m;j++) { cin>>cost[i][j+n]; cost[j+n][i]=-cost[i][j+n]; } if(flag) { memset(g,0,sizeof(g)); for(i=1;i<=n;i++)//容量 { g[source][i]=order[i][t]; for(j=1;j<=m;j++) { g[i][j+n]=supply[j][t]; } sum+=order[i][t]; } for(i=1;i<=m;i++)//容量 { g[i+n][sink]=supply[i][t]; provide+=supply[i][t]; } if(sum>provide) flag=false; if(flag) ans+=min_max(source ,sink); } } if(flag) cout<<ans<<endl; else cout<<-1<<endl; } return 0; }