每天(?)一道LeetCode(10) Spiral Matri

Array

059. Spiral Matrix II

Given a positive integer, generate a square matrix filled with elements from to in spiral order.
就是给定一个，将元素按照顺时针组成一个的矩阵
举个例子
,Output:

Solutions

class Solution:
    def generateMatrix(self, n):
        """
        :type n: int
        :rtype: List[List[int]]
        """
        matrix=[[0 for _ in range(n)] for _ in range(n)]
        counter = 1
        i,j=0,0
        top,right,bottom,left=0,n-1,n-1,0
        direction = "right"
        while counter <= n*n:
            matrix[i][j] = (counter)
            counter += 1
            if direction == "right":
                if j+1 <= right:
                    j += 1
                else:
                    right -= 1
                    i += 1
                    direction = "down"
            elif direction == "down":
                if i+1 <= down:
                    i += 1
                else:
                    down -= 1
                    j -= 1
                    direction = "left"
            elif direction == "left":
                if j-1 >= left:
                    j -= 1
                else:
                    left += 1
                    i -= 1
                    direction = "up"
            else:
                if i-1 >= up:
                    i -= 1
                else:
                    j += 1
                    up += 1
                    direction = "right"
                    
        return matrix

OR

class Solution(object):
    # @return a list of lists of integer
    def generateMatrix(self, n):
        matrix = [[0 for _ in xrange(n)] for _ in xrange(n)]

        left, right, top, bottom, num = 0, n - 1, 0, n - 1, 1

        while left <= right and top <= bottom:
            for j in xrange(left, right + 1):
                matrix[top][j] = num
                num += 1
            for i in xrange(top + 1, bottom):
                matrix[i][right] = num
                num += 1
            for j in reversed(xrange(left, right + 1)):
                if top < bottom:
                    matrix[bottom][j] = num
                    num += 1
            for i in reversed(xrange(top + 1, bottom)):
                if left < right:
                    matrix[i][left] = num
                    num += 1
            left, right, top, bottom = left + 1, right - 1, top + 1, bottom - 1

        return matrix