Codeforces Round #385 (Div. 2) B

就是判断矩形

水题，自己太菜了

#include<cstdio>#include<cstring>#include<algorithm>#include<iostream>using namespace std;int main(){int n,m;char a[505][505];scanf("%d %d",&n,&m);for(int i=0;i<n;i++)scanf("%s",a[i]);int x1=-1,x2=-1,x3=-1,x4=-1,y1=-1,y2=-1,y3=-1,y4=-1;for(int i=0;i<n;i++){for(int j=0;j<m;j++){if(a[i][j]=='X'){x1=i; y1=j;for(int k=m-1;k>=0;k--){if(a[i][k]=='X'){x2=i; y2=k; break;}}break;}    }    if(x1!=-1) break;}for(int i=n-1;i>=0;i--){for(int j=0;j<m;j++){if(a[i][j]=='X'){x3=i; y3=j;for(int k=m-1;k>=0;k--){if(a[i][k]=='X'){x4=i; y4=k; break;}}break;}    }    if(x3!=-1) break;}if(y1!=y3||y2!=y4||x1!=x2||x3!=x4) printf("NO\n");else {int t=0;for(int i=x1;i<=x3;i++){for(int j=y1;j<=y2;j++)if(a[i][j]=='.') {t=1; break;}if(t==1) break;}if(t) printf("NO\n");else printf("YES\n"); } }