283. Move Zeroes

🟩 Easy

Question

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

Example:

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

Note:

1. You must do this in-place without making a copy of the array.

2. Minimize the total number of operations.

Two Pointer Approach

One pointer for zero, one for non-zeros. Swap elements to move non-zero element forward.

Complexity

• Time complexity: O(n)

• Space complexity: O(1)

Code

def moveZeroes(self, nums: List[int]) -> None:
    """ Do not return anything, modify nums in-place instead."""
    if len(nums)==0 or not nums:
        return
    j=0
    for i in range(len(nums)):
        if nums[i]: # nums[i] != 0
            if not nums[j]: # nums[j] == 0
                nums[i], nums[j] = nums[j], nums[i] #swap
            j +=1