Move Zeros to the End

Reorder a list in-place so all zeros are at the end while keeping the relative order of non-zero elements.

lists in-place two-pointer order

Write a function `move_zeros_to_end(nums)` that takes a list of integers `nums` and modifies it **in-place** so that all zeros are moved to the end of the list, preserving the relative order of the non-zero elements. The function should return the same list object (after modification).

**Requirements:**
- Modify the input list in-place.
- Do not create a new list as the final result (you may use temporary variables).
- The relative order of non-zero elements must be preserved.
- All zero elements must be at the end.
- The function should return the modified list.

Constraints

- The list may be empty or contain any number of integers (including negatives).
- The list length is between 0 and 10^4.
- Each element is an integer in the range [-10^4, 10^4].
- Time complexity: O(n) expected.
- Space complexity: O(1) extra space (besides the input list).

Example

>>> nums = [0, 1, 0, 3, 12]
>>> result = move_zeros_to_end(nums)
>>> result is nums
True
>>> nums
[1, 3, 12, 0, 0]

>>> nums = [0, 0, 0]
>>> move_zeros_to_end(nums)
[0, 0, 0]

10 points ~15 min

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Hints

Use two pointers: one to iterate and one to track where the next non-zero should be placed.

First pass: move all non-zero elements to the front in order.

After moving non-zeros, fill the remaining positions with zeros.

Test Results

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