题解 | #回型矩阵#

#include <iostream>
using namespace std;

int main() {
    int n;
    cin >> n;
    int row = 0;
    int col = 0;
    int top_bound = 0;
    int left_bound = 0;
    int right_bound = n - 1;
    int bottom_bound = n - 1;
    int a[n][n];
    int i = 1;
    int direction = 0;
    while (1)
    {
        if (direction == 0)
        {
            if (col == right_bound)
            {
                direction = 1;
                top_bound++;
            }   
            else
            {
                a[row][col] = i;
                i++;
                col++;
            } 
        }
        if (direction == 1)
        {
            if (row == bottom_bound)
            {
                direction = 2;
                right_bound--;
            }   
            else
            {
                a[row][col] = i;
                i++;
                row++;
            } 
        }
        if (direction == 2)
        {
            if (col == left_bound)
            {
                direction = 3;
                bottom_bound--;
            }   
            else
            {
                a[row][col] = i;
                i++;
                col--;
            } 
        }
        if (direction == 3)
        {
            if (row == top_bound)
            {
                direction = 0;
                left_bound++;
            }   
            else
            {
                a[row][col] = i;
                i++;
                row--;
            } 
        }
        if (i == n * n + 1)
            break;

    }
    for (int i = 0; i < n; ++i)
    {
        for (int j = 0; j < n; ++j)
        {
            cout << a[i][j] << " ";
        }
        cout << endl;
    }
}
// 64 位输出请用 printf("%lld")

模拟数组，很经典的题目，按照贪吃蛇的写法写很清楚。