Move Zeroes
Description: Given array nums, move all zeroes to the end while keeping the relative order of the other elements. Return the modified array.
Example 1:
Input: nums = [0,1,0,3,12]
Output: [1,3,12,0,0]
Explanation: Non-zero elements keep their order
Example 2:
Input: nums = [1,2,3]
Output: [1,2,3]
Explanation: No zeroes, array unchanged
Constraints:
1 <= nums.length <= 10⁴
-2³¹ <= nums[i] <= 2³¹ - 1
Recommended time and space complexity
Aim for O(n) time and O(1) space — without creating a new array.
Hint 1
Creating a new array is easy, but the task asks for in-place.
Hint 2
Keep a pointer to where the next non-zero element should go.
Hint 3
Move all non-zero elements to the front, then fill the tail with zeroes.