题解 | 回型矩阵

#include <stdio.h>
int main()
{
    int n = 0;
    int k = 1;
    scanf("%d", &n);
    int a[20][20];
    int up = 0, right = n - 1, down = n - 1, left = 0;
    while (k <= n * n)
    {
        for (int i = up; i <= right; i++)
        {
            a[up][i] = k++;
        }
        up++;
        for (int i = up; i <= down; i++)
        {
            a[i][down] = k++;
        }
        right--;
        for (int i = right; i >= left; i--)
        {
            a[down][i] = k++;
        }
        down--;
        for (int i = down; i >= up; i--)
        {
            a[i][left] = k++;
        }
        left++;
    }
    for (int i = 0; i < n; i++)
    {
        for (int j = 0; j < n; j++)
        {
            printf("%d", a[i][j]);
            printf(" ");
        }
        printf("\n");
    }
    return 0;
}