Move Zeroes

Shift all zeroes to the end while keeping the relative order of non-zero elements.

arrays in-place two-pointers

Write a function `move_zeroes(nums)` that takes a list of integers `nums` and modifies the list **in-place** so that all zeros are moved to the end of the list, while the relative order of all non-zero elements is preserved. The function should return the modified list (which is the same list object as the input). Do not create a copy of the list; the modification must be done by rearranging elements in the original list.

Examples:
- `move_zeroes([0,1,0,3,12])` returns `[1,3,12,0,0]` and the input list becomes `[1,3,12,0,0]`.
- `move_zeroes([0,0,1])` returns `[1,0,0]`.
- `move_zeroes([1,2,3])` returns `[1,2,3]`.
- `move_zeroes([0,0,0])` returns `[0,0,0]`.
- `move_zeroes([])` returns `[]`.

Implement the function such that it performs the operation in O(n) time and O(1) extra space.

Constraints

- Input list length: 0 ≤ n ≤ 10^5.
- Each element is an integer.
- Must modify the list in-place.
- Time complexity O(n), extra space O(1).

Example

>>> nums = [0,1,0,3,12]
>>> move_zeroes(nums)
[1,3,12,0,0]
>>> nums
[1,3,12,0,0]

>>> nums = [0,0,1]
>>> move_zeroes(nums)
[1,0,0]
>>> nums
[1,0,0]

>>> nums = [1,2,3]
>>> move_zeroes(nums)
[1,2,3]
>>> nums
[1,2,3]

10 points ~15 min

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Hints

Use a slow pointer that marks the position where the next non-zero element should go.

Iterate with a fast pointer; whenever it sees a non-zero, place it at the slow pointer and increment the slow pointer.

After the pass, fill the rest of the list (from slow pointer to end) with zeros.

Make sure to return the list at the end.

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