202. Move Zeroes

Use a slow pointer to track the position for the next non-zero element. Fast pointer scans through the array.

Approach

1. Slow pointer marks the position for the next non-zero.
2. Fast pointer scans left to right.
3. When fast finds a non-zero, swap with slow position and advance slow.

Complexity

• Time: O(n)
• Space: O(1)

class Solution {
    public void moveZeroes(int[] nums) {
        int slow = 0;
        for (int fast = 0; fast < nums.length; fast++) {
            if (nums[fast] != 0) {
                int temp = nums[slow];
                nums[slow] = nums[fast];
                nums[fast] = temp;
                slow++;
            }
        }
    }
}