Move Zeroes — Leetcode

Topic: Array
Difficulty: Easy
Question Number: 283

Problem statement:
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]

Explanation:
The general idea is to scan the array twice.

The first scan uses two pointers: one index pointer to maintain a non-zero subarray( modify the original array ), and the other index to loop through the original array. If the current element being examined is 0, then skip; if it’s not 0, move it to the non-zero subarray.

After the first round, all the non-zero elements should be squeezed to the left part of the original array. So the second round we just add zeros to the empty slots.

Code:

class Solution {
  public void moveZeroes(int[] nums) {
    int i = 0;
    for (final int num : nums)
      if (num != 0)
        nums[i++] = num;

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

Thank you
Oshi Raghav