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This approach uses two pointers: one to track the position for the next non-zero element and the other to iterate through the array. We move all non-zero elements to the beginning of the array using these two pointers and fill the remaining positions with zeroes.
Time Complexity: O(n), where n is the length of the array. We make a single pass through the array.
Space Complexity: O(1), as we perform the operation in place.
1public class Solution {
2 public void moveZeroes(int[] nums) {
3 int lastNonZeroFoundAt = 0;
4 for (int i = 0; i < nums.length; i++) {
5 if (nums[i] != 0) {
6 nums[lastNonZeroFoundAt++] = nums[i];
7 }
8 }
9 for (int i = lastNonZeroFoundAt; i < nums.length; i++) {
10 nums[i] = 0;
11 }
12 }
13}In this Java solution, we use a similar approach, using an integer lastNonZeroFoundAt to track where to place the next non-zero number found as we iterate through nums.
This method uses a two-pointer technique where we place one pointer at the beginning of the array and the other to iterate through the array. Whenever we encounter a non-zero element, we swap it with the first pointer's position, allowing us to effectively move zeroes to the end by swapping.
Time Complexity: O(n), single iteration with swaps.
Space Complexity: O(1), in-place swaps.
1defThe Python version leverages tuple unpacking to swap elements at positions j and i. The j pointer ensures that swaps occur only with zeros, keeping all non-zero elements ordered.