19第一场 nowcoder F 爆搜

#include <bits/stdc++.h>
#define ll long long
using namespace std;
ll a[30][30];
ll d[30];
vector<int> v;
ll n,ans;
void dfs(int p,ll sum){
	if(v.size()==n){
		ans = max(ans,sum);
		return ;
	}
	if(p>2*n)return ;
	ll now = d[p];
	for(int i=0;i<v.size();i++){
		now-=2*a[p][v[i]];
	}
	v.push_back(p);
	dfs(p+1,sum+now);
	v.pop_back();
	dfs(p+1,sum);
}
int main()
{
	ans= 0;
	scanf("%lld",&n);
	for(int i=1;i<=2*n;i++){
		for(int j=1;j<=2*n;j++){
		  	scanf("%lld",&a[i][j]);	
		  	d[i]+=a[i][j];
		}
	}
	dfs(1,0);
	printf("%lld",ans);
	return 0;
}