Bullet
Problem Description
In GGO, a world dominated by gun and steel, players are fighting for the honor of being the strongest gunmen. Player Shino is a sniper, and her aimed shot kills one monster at a time. Now she is in an n×nn \times nn×n map, and there are monsters in some grids. Each monster has an experience. As a master, however, Shino has a strange self-restrain. She would kill at most one monster in a column, and also at most one in a row. Now she wants to know how to get max experience, under the premise of killing as many monsters as possible.
Input
The first line contains an integer nnn
Then n lines follow. In each line there are n integers, and AijAijAij represents the experience of the monster at grid (i,j)(i,j)(i,j). If Aij=0Aij=0Aij=0, there is no monster at grid (i,j)(i,j)(i,j).
Output
One integer, the value of max experience.
Sample Input
2 2 0 1 8
Sample Output
2
Hint
Source
#define happy #include<bits/stdc++.h> using namespace std; #define ll long long #define rep(i,a,b) for(int i=a;i<=b;i++) #define all(a) (a).begin(),(a).end() #define pll pair<ll,ll> #define vi vector<int> #define pb push_back const int inf=0x3f3f3f3f; ll rd(){ ll x=0,f=1;char ch=getchar(); while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();} while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();} return x*f; } const int N=505; int a[N][N]; int x[N],y[N]; int n,tans,ans; ll sum; void dfs(int k,ll d){ if(k==n+1){ if(d>=sum){ sum=d; ans=min(ans,tans); } return ; } bool f=false; for(int i=1;i<=n;i++){ if(a[k][i]==0||x[i]||y[k])continue; f=true; int tt=tans; x[i]=y[k]=1; tans=min(tans,a[k][i]); dfs(k+1,d+a[k][i]); x[i]=y[k]=0; tans=tt; } if(!f)dfs(k+1,d); } int main(){ #ifdef happy freopen("in.txt","r",stdin); #endif n=rd(); rep(i,1,n)rep(j,1,n) a[i][j]=rd(); sum=0; tans=ans=inf; dfs(1,0); printf("%d\n",ans); }