• 分类：Array
• 时间复杂度: O(n*m)

59. Spiral Matrix II

Given a positive integer n, generate a square matrix filled with elements from 1 to n2 in spiral order.

Example:

Input: 3
Output:
[
 [ 1, 2, 3 ],
 [ 8, 9, 4 ],
 [ 7, 6, 5 ]
]

代码：

方法:

class Solution:
    def generateMatrix(self, n: 'int') -> 'List[List[int]]':
        
        if n==0:
            return [[]]
        
        matrix=[[0 for i in range(n)] for i in range(n)]
        
        num=1
        top,left,row,col=0,0,0,0
        right,bottom=n-1,n-1
        
        while top<bottom and left<right:
            while col<right:
                matrix[row][col]=num
                col+=1
                num+=1
            while row<bottom:
                matrix[row][col]=num
                row+=1
                num+=1
            while col>left:
                matrix[row][col]=num
                col-=1
                num+=1
            while row>top:
                matrix[row][col]=num
                row-=1
                num+=1
            top+=1
            left+=1
            col+=1
            row+=1
            bottom-=1
            right-=1
        
        if top==bottom and left==right:
            matrix[top][left]=num
        
        return matrix

讨论：

1.谨记四个角的坐标不要写错了。。。