代码如下

#include <iostream>
using namespace std;
int main(int argc, const char * argv[]) {
    char fistChar = 'A';
    int line = 0;
    cin >> line;
    for(int i=0;i<line;i++) {
        for(int j=0;j<line;j++) {
            char temp = char(fistChar + j);
          
            temp = (temp - 'A') % 26 + 'A';
            cout << temp;
        }
        fistChar = fistChar + 1;
        cout << endl;
    }
    return 0;
}