poj2400

题解：

最少平均分值是等于最佳匹配的权值和除上一个总的点数2*n

注意输入反过来

代码：

#include<cstdio>
#include<cstring>
#include<cmath>
#include<algorithm>
const int N=;
int n,lx[N],ly[N],T,w[N][N],k,d[N],t,ans,num,h[N],px[N],py[N];
int dfs1(int x)
{
    px[x]=;
    for (int i=;i<=n;i++)
     {
        if (py[i])continue;
        t=lx[x]+ly[i]-w[x][i];
        if (!t)
         {
            py[i]=;
            if (!d[i]||dfs1(d[i]))
             {
                d[i]=x;
                return ;
             }
         }
     }
    return ;
}
void dfs2(int x,int sum)
{
    if (sum>ans) return;
    if (x>n)
     {
        if (sum!=ans)return;
        printf("Best Pairing %d\n",++num);
        for (int i=;i<=n;i++)
         printf("Supervisor %d with Employee %d\n",i,h[i]);
        return;
     }
    for (int i=;i<=n;i++)
     if (!py[i])
      {
        h[x]=i;
        py[i]=;
        dfs2(x+,sum-w[x][i]);
        py[i]=;
      }
    return;
}
int main()
{
    scanf("%d",&T);
    for (int u=;u<=T;u++)
     {
        scanf("%d",&n);
        for (int i=;i<=n;i++)
         for (int j=;j<=n;j++)
          {
            scanf("%d",&k);
            w[k][i]=-j;
          }
        for (int i=;i<=n;i++)
         for (int j=;j<=n;j++)
          {
            scanf("%d",&k);
            w[i][k]+=-j;
          }
        memset(ly,,sizeof(ly));
        for (int i=;i<=n;i++)
         {
            lx[i]=w[i][];
            for (int j=;j<=n;j++)
             if (lx[i]<w[i][j])lx[i]=w[i][j];
         }
        memset(d,,sizeof(d));
        for (int i=;i<=n;i++)
         while ()
          {
            memset(px,false,sizeof(px));
            memset(py,false,sizeof(py));
            if (dfs1(i)) break;
            t=1e9;
            for (int j=;j<=n;j++)
             if (px[j])
              for (int k=;k<=n;k++)
               if (!py[k]&&lx[j]+ly[k]-w[j][k]<t)
                t=lx[j]+ly[k]-w[j][k];
            for (int j=;j<=n;j++)
             {
                if (px[j]) lx[j]-=t;
                if (py[j]) ly[j]+=t;
             }
          }
        ans=;
        for (int i=;i<=n;i++)
         if (d[i]!=)ans-=w[d[i]][i];
        printf("Data Set %d, Best average difference: %.6f\n",u,ans*0.5/n);
        num=;
        memset(h,,sizeof(h));
        memset(py,false,sizeof(py));
        dfs2(,);
        if (u<T)puts("");
     }
    return ;
}