NOI 题库 1792

#include "bits/stdc++.h"

using namespace std ;
const int maxN = 1100 ; 

char mp[ maxN ][ maxN ] ;
bool limit [ maxN ][ maxN ] ;

int destination_x , destination_y ; 
bool Get_Target ; 


void DFS ( const int N , const int xi , const int yi ) {
        if ( Get_Target ) return ;
        if ( xi == destination_x && yi == destination_y ) {
                Get_Target = true ; 
                cout << "YES" << endl ; 
                return ; 
        }
        if ( mp[ xi ][ yi ] == ‘#‘ ) return ;
        if ( !limit[ xi ][ yi ] ) return ;
        else {
                mp[ xi ][ yi ] = ‘#‘ ;        
                if ( limit[ xi - 1 ][ yi ] ) DFS ( N , xi - 1 , yi ) ;
                if ( limit[ xi + 1 ][ yi ] ) DFS ( N , xi + 1 , yi ) ;
                if ( limit[ xi ][ yi - 1 ] ) DFS ( N , xi , yi - 1 ) ;
                if ( limit[ xi ][ yi + 1 ] ) DFS ( N , xi , yi + 1 ) ;
        }
} 

void Re_Init ( int n ) {
        for ( int i=0 ; i<n ; ++i ) {
                for ( int j=0 ; j<n ; ++j ) {
                        limit [ i ][ j ] = true ; 
                }
        }
}

int main ( ) {
        int T ; 
        scanf ( "%d" , &T ) ;
        while ( T-- ) {
                int N , start_x , start_y ;
                Get_Target = false ;
                scanf ( "%d" , &N ) ;
                Re_Init ( N ) ;
                getchar ( ) ;
                for ( int i=0 ; i<N ; ++i ) {
                        for ( int j=0 ; j<N ; ++j ) {
                                mp[ i ][ j ] = getchar ( ) ;
                        }
                        getchar ( ) ;
                }
                scanf ( "%d%d%d%d" , &start_x , &start_y , &destination_x , &destination_y ) ; 
                if ( mp[ start_x ][ start_y ] == ‘#‘ || mp[ destination_x ][ destination_y ] == ‘#‘ ) {cout << "NO" << endl ;continue ;} 
                DFS ( N , start_x , start_y ) ;
                if ( !Get_Target ) cout << "NO" << endl ; 
                memset ( limit , false , sizeof ( limit ) ) ;
        }
        return 0;
}