题解 | #回型矩阵#

思路：

处理好边界问题，利用循环模拟生成回型矩阵即可

#include <bits/stdc++.h>
using namespace std;

int ar[21][21];

int main(){
    std::ios::sync_with_stdio(false);
    std::cin.tie(0);
    int n,left = 1,right,up = 1,down,count = 0;    //定义边界变量
    cin>>n;
    right = down = n;
    while(count < n*n){
        for(int i = left;i <= right;i++)
            ar[up][i] = (++count);
        up++;
        for(int i = up;i <= down;i++)
            ar[i][right] = (++count);
        right--;
        for(int i = right;i >= left;i--)
            ar[down][i] = (++count);
        down--;
        for(int i = down;i >= up;i--)
            ar[i][left] = (++count);
        left++;
    }
    for(int i = 1;i <= n;i++){
        for(int j = 1;j <= n;j++)
            cout<<ar[i][j]<<' ';
        cout<<'\n';
    }
    return 0;
}