题解 | 回型矩阵

n = int(input())
# 创建一个 n x n 的矩阵，初始化为 0
matrix = [[0] * n for _ in range(n)]
count = 1  # 当前填充的数字
top, bottom, left, right = 0, n-1, 0, n-1  # 初始边界
while count <= n * n:
        # 从左到右填充上边界
        for i in range(left, right + 1):
            matrix[top][i] = count
            count += 1
        top += 1

        # 从上到下填充右边界
        for i in range(top, bottom + 1):
            matrix[i][right] = count
            count += 1
        right -= 1

        # 从右到左填充下边界
        if top <= bottom:
            for i in range(right, left - 1, -1):
                matrix[bottom][i] = count
                count += 1
            bottom -= 1

        # 从下到上填充左边界
        if left <= right:
            for i in range(bottom, top - 1, -1):
                matrix[i][left] = count
                count += 1
            left += 1

# 打印矩阵，每个元素后跟一个空格，行末换行
for i in range(n):
    # 格式化打印，确保数字对齐（可选，根据需要调整）
    print(' '.join(str(matrix[i][j]) for j in range(n)))