CA 13 - Move Zeros

Problem
Move Zeroes
You are given an integer array nums.
Your task is to move all 0s to the end while maintaining the relative order of non-zero elements.

The operation must be done in-place, without using extra space.

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

Approach

The idea is to shift all non-zero elements forward and fill the remaining positions with zeros.

Steps:

• Use a pointer insert_pos to track where the next non-zero element should go
• Traverse the array:
• If the element is non-zero, place it at insert_pos and move the pointer forward
• After traversal, fill the rest of the array with 0s

This keeps the order intact and avoids extra space.

Complexity:
Time Complexity: O(n)
Space Complexity: O(1)

def moveZeroes(nums):
    insert_pos = 0
    for num in nums:
        if num != 0:
            nums[insert_pos] = num
            insert_pos += 1
    for i in range(insert_pos, len(nums)):
        nums[i] = 0
    return nums
nums = [0, 1, 0, 3, 12]
print(moveZeroes(nums))