leetcode59

class Solution:
    def generateMatrix(self, n: int) -> 'List[List[int]]':
        res = [[0 for _ in range(n)]for _ in range(n)]
        x,y = 0,0
        count = 1
        while x <= n and y <= n:
            for j in range(y,n):
                res[x][j] = count
                count += 1
            for i in range(x + 1,n):
                res[i][n - 1] = count
                count += 1
            for j in range(n - 2,y - 1,-1):
                res[n - 1][j] = count
                count += 1
            for i in range(n - 2,x,-1):
                res[i][y] = count
                count += 1
            
            x += 1
            y += 1
            n -= 1
        return res

本题思路同leetcode54一样，二维数组螺旋遍历。

起点坐标：沿主对角线，从左上向右下移动，即 x += 1, y += 1

终点坐标：每次缩小n的范围，即 n -= 1

能完整访问一个"外圈"，就可以按照相同的方式，访问"内圈"，一层一层的访问。