動機

醍醐灌頂!!

Problem

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Note that you must do this in-place without making a copy of the array.

 

Example 1:

Input: nums = [0,1,0,3,12]Output: [1,3,12,0,0]

Example 2:

Input: nums = [0]Output: [0]

 

Constraints:

  • 1 <= nums.length <= 104
  • -231 <= nums[i] <= 231 - 1

 

Follow up: Could you minimize the total number of operations done?

Sol

簡單卻深刻，當初是先想到bubble去跑

因為只有0，所以只要把有數字的往前提(用一個index去追蹤)，之後就是從後面開始塞0就好

class Solution:
    def moveZeroes(self, nums: List[int]) -> None:
        zeros = i = 0
        for n in nums:
            if n == 0:
                zeros += 1
            else:
                nums[i] = n
                i+=1
        
        i = -1
        while zeros > 0:
            nums[i] = 0
            i -= 1
            zeros -= 1