Mirror Grid

Mirror Grid

The question :

Given a n * n The rectangular , Rotate it 90°,180°,270° Keep the same after . Ask how many steps you need to complete at least .

Ideas :

According to the meaning of the title, this matrix must be a centrosymmetric figure , So traverse every layer of this rectangle , Check every time 0 More or less 1 Just more

a key : ergodic matrix

AC Code :

#include <iostream>
#include <algorithm>

using namespace std;
int a[105][105];

int main(){
	int t;cin >> t;
	while(t --){
		int n;cin >> n;
		for(int i = 1;i <= n;i ++)
			for(int j = 1;j <= n;j ++){
				char x;cin >> x;
				a[i][j] = x - '0';
			}
		
		int ans = 0;
		for(int i = 1;i <= (n + 1) / 2;i ++){
			for(int j = 1;j <= n / 2;j ++){
				int x = a[i][j] + a[j][n-i+1] + a[n-i+1][n-j+1] + a[n-j+1][i];
				ans += min(4 - x,x);
			}
		}
		cout << ans << endl;
	}
	return 0;
}