P1129 [ZJOI2007] 矩阵游戏

Posted 2023-03-22 towboa

 

 

 

#include<iostream>
#include<algorithm>
#include <queue>
using namespace std ;
const int N=6e4,M=1e5+10;
  const int inf =1e9+7;
  
 int all=1,hd[N],go[M],w[M],nxt[M];
   
 int S,T,n,m;
 int dis[M],ans=0,now[M];
   
 void add_(int x,int y,int z)
     nxt[++all]=hd[x]; hd[x]=all; go[all]=y;
     w[all]=z;
     swap(x,y);
     nxt[++all]=hd[x]; hd[x]=all; go[all]=y;
     w[all]=0;
 
  bool bfs()
     for(int i=0;i<M;i++)dis[i]=inf;
     queue<int> q;
     q.push(S);
     now[S]=hd[S];
     dis[S]=0;
       
     while(q.empty()==0)
         int x=q.front();
         q.pop();
         for(int i=hd[x];i;i=nxt[i])
             int y=go[i];
             if(w[i]>0&&dis[y]==inf)
                 dis[y]=dis[x]+1;
                 now[y]=hd[y];
                 q.push(y);
                 if(y==T) return 1;
             
         
     
     return 0;
 
 int dfs(int x,int sum)
     if(x==T) return sum;
     int k,res=0;
       
     for(int i=now[x];i&& sum ;i=nxt[i])
         now[x]=i;
         int y=go[i];
         if(w[i]>0&&(dis[y]==dis[x]+1))
             k=dfs(y,min(sum,w[i]));
             if(k==0) dis[y]=inf;
             w[i]-=k;
             w[i^1]+=k;
             res+=k;
             sum-=k;
         
     
     return res;
 
 signed main()
 	int tes;cin>>tes;
 	while(tes--)
	 	cin>>n;
	 	int i,j,x;for(i=0;i<=2*n;i++)now[i]=hd[i]=0;all=1;
	 	
	 	S=0,T=2*n+1;
	 	for(i=1;i<=n;i++) add_(S,i,1),add_(i+n,T,1);
	 	for(i=1;i<=n;i++) 
	 	for(j=1;j<=n;j++)
	 		cin>>x; if(x) add_(i,j+n,1);
	 	
	 	int ans=0;
	 	while(bfs())ans+=dfs(S,inf);
	 	cout<<(ans>=n?"Yes":"No")<<endl;