283. Move Zeroes

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

Example:

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

Note:

    You must do this in-place without making a copy of the array.
    Minimize the total number of operations.

public void moveZeroes(int[] nums) {
    int l = 0, r = 0;
    // l -> left most 0
    // r -> the first none 0 starting from l
    while(r < nums.length) {
        while(l < nums.length && nums[l] != 0) l++;
        r = l;
        while(r < nums.length && nums[r] == 0) r++;
        if(r < nums.length) swap(nums, l, r);
    }
}

public void moveZeroes(int[] nums) {
    if (nums == null || nums.length == 0) return;

    int insertPos = 0;
    for (int num: nums) {
        if (num != 0) nums[insertPos++] = num;
    }

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