283. Move Zeroes

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Note that you must do this in-place without making a copy of the array.

Example 1:

Input: nums = [0,1,0,3,12]
Output: [1,3,12,0,0]

Example 2:

Input: nums = [0]
Output: [0]

Solution:

class Solution {
    public void moveZeroes(int[] nums) {
        int n = nums.length;
        int left = 0;

        for (int right = 0; right < n; right++){
            if (nums[right] != 0){
                int tmp = nums[left];
                nums[left] = nums[right];
                nums[right] = tmp;
                left++;
            }
        }

        return;
    }
}

// TC: O(n)
// SC: O(1)

class Solution {
    public void moveZeroes(int[] nums) {
        int n = nums.length;

        int left = 0;

        for (int i = 0; i < n; i++){
            int cur = nums[i];

            if (nums[i] == 0){
                continue;
            }

            swap(nums, left, i);
            left++;

        }


        return;
    }

    private void swap(int[] nums, int i, int j){
        int tmp = nums[i];
        nums[i] = nums[j];
        nums[j] = tmp;
    }
}


// TC: O(n)
// SC: O(1)

class Solution {
    public void moveZeroes(int[] nums){
        // base case
        if (nums == null || nums.length <= 1){
            return;
        }

        int slow = 0;
        int fast = 0;

        while(fast < nums.length){
            if (nums[fast] != 0){
                nums[slow] = nums[fast];
                slow++;
                fast++;
            }else{
                // nums[slow] == 0
                fast++;
            }
        }


        while(slow < nums.length){
            nums[slow] = 0;
            slow++;
        }
    }


}
// TC: O(n)
// SC: O(1)
/*
[1,3,12,3,12]
       s
             f
*/