题解 | #回型矩阵#

using namespace std;
int a[20][20];
int main()
{
    int n;
    cin >> n;
    int x = 1;
    int i = 0;
    int j = 0;
    while(x <= n * n)
    {
        while(a[i][j] == 0 && j < n)
        {
            a[i][j] = x;
            x++;
            j++;
        }
        j--;
        i++;
        while(a[i][j] == 0 && i < n)
        {
            a[i][j] = x;
            x++;
            i++;
        }
        i--;
        j--;
        while(a[i][j] == 0 && j >= 0)
        {
            a[i][j] = x;
            x++;
            j--;
        }
        i--;
        j++;
        while(a[i][j] == 0 && i >= 0)
        {
            a[i][j] = x;
            x++;
            i--;
        }
        i++;
        j++;
    }
    
    for(int i = 0;i < n;i++)
    {
        for(int j = 0;j < n;j++)
        {
            cout << a[i][j] << " ";
        }
        cout << endl;
    }
    return 0;
}