Codeforces #828B: Black Square 题解

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如果没有黑格子直接输出1

记录当前所有黑格子中列最靠左的minc，最靠右的maxc，行最靠上的minr，最靠下的maxr

如果maxc-minc+1=maxr-minr+1，那么一定能填出正方形，只要拿面积减去black个数即可

如果不等，那答案最小的正方形边长一定是max(maxr-minr+1,maxc-minc+1)

也就是填成长方形以后再补成正方形

看看剩下的行或列够不够补成正方形即可

#include <cstdio>#include <iostream>#include <cstring>#include <string>#include <cmath>#include <algorithm>#include <cstdlib>#include <utility>#include <map>#include <stack>#include <set>#include <vector>#include <queue>#include <deque>#define x first#define y second#define mp make_pair#define pb push_back#define LL long long#define Pair pair<int,int>#define LOWBIT(x) x & (-x)using namespace std;const int INF=0x7ffffff;int n,m;char a[101][101];int main (){int i,j;scanf("%d%d",&n,&m);for (i=1;i<=n;i++) scanf("%s",a[i]+1);int minc=INF,maxc=-INF,minr=INF,maxr=-INF,cnt=0;for (i=1;i<=n;i++)for (j=1;j<=m;j++)if (a[i][j]=='B'){cnt++;minc=min(minc,j);maxc=max(maxc,j);minr=min(minr,i);maxr=max(maxr,i);}if (cnt==0){printf("1\n");return 0;}if (maxr-minr==maxc-minc){printf("%d\n",(maxr-minr+1)*(maxr-minr+1)-cnt);return 0;}if (maxr-minr<maxc-minc){int ss=maxc-minc+1;int rr=maxr-minr+1,cc=maxc-minc+1;int rem=n-rr;if (rem<cc-rr)printf("-1\n");elseprintf("%d\n",ss*ss-cnt);}else{int ss=maxr-minr+1;int rr=maxr-minr+1,cc=maxc-minc+1;int rem=m-cc;if (rem<rr-cc)printf("-1\n");elseprintf("%d\n",ss*ss-cnt);}return 0;}

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