Codeforces Round #514 (Div. 2) B. Forgery(思维+暴力)

#include <bits/stdc++.h>
#define maxn 1005
using namespace std;
char a[maxn][maxn],b[maxn][maxn];
int n,m;

void Fun(int x,int y)
{
	if(a[x+1][y] == '#' && a[x+2][y] == '#' && a[x][y+1] == '#' && a[x][y+2] == '#' && a[x+1][y+2] == '#' && a[x+2][y+2] == '#' && a[x+2][y+1] == '#'){
		b[x][y] = '#';
		b[x+1][y] = '#';
		b[x+2][y] = '#';
		b[x][y+1] = '#';
		b[x][y+2] = '#';
		b[x+1][y+2] = '#';
		b[x+2][y+2] = '#';
		b[x+2][y+1] = '#';
	}
}

int main()
{
	scanf("%d%d",&n,&m);
	for(int i=0;i<n;i++)scanf("%s",a[i]);
	memset(b,'.',sizeof(b));
	
	for(int i=0;i<n-2;i++){
		for(int j=0;j<m-2;j++){
			if(a[i][j] == '#'){
				Fun(i, j);
			}
		}
	}
	bool flag = false;
	for(int i=0;i<n;i++){
		for(int j=0;j<m;j++){
			if(a[i][j] != b[i][j]){
				flag = true;
				break;
			}
		}
	}
	if(flag == false){
		puts("YES");
	}
	else{
		puts("NO");
	}
	return 0;
}