#include<stdio.h>
const int N=21;
int n,map[N][N],ans,f[1<<20];
bool v[1<<20];
inline bool find(int x,int s)
{return s>>(x-1)&1;}
inline int max(int a,int b)
{if(a>b)return a;return b;}
int main()
{
  //freopen("poj2531.in","r",stdin);
  //freopen("poj2531.out","w",stdout);
  scanf("%d",&n);
  for(int i=1;i<=n;i++)
    for(int j=1;j<=n;j++)
    scanf("%d",&map[i][j]);
  int s=(1<<n)-1;
  for(int i=1;i<s;i++)
  if(!v[i])
  {
    v[i]=1;
    v[i^s]=1;
    int j=1;
    for(;j<=n;j++)
      if(find(j,i))
      break;
    f[i]=f[i-(-i&i)];
    for(int k=1;k<=n;k++)
      if(find(k,i-(-i&i)))
      f[i]-=map[j][k];
      else f[i]+=map[j][k];
    f[i^s]=f[i];
    ans=max(ans,f[i]);
  }
  printf("%d\n",ans);
}
    
    
  

• Re:赞一个 (843) liuyuhong 2016-01-24 18:22:13