[LintCode] Move Zeroes

Problem

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.

Notice

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

Example

Given nums = [0, 1, 0, 3, 12], after calling your function, nums should be [1, 3, 12, 0, 0].

Solution

A too-clever method

class Solution {
    public void moveZeroes(int[] nums) {
        int i = 0, j = 0;
        while (i < nums.length && j < nums.length) {
            if (nums[i] != 0) {
                int temp = nums[i];
                nums[i] = nums[j];
                nums[j] = temp;
                j++;
            }
            i++;
        }
    }
}

A just-so-so method

public class Solution {
    public void moveZeroes(int[] nums) {
        int i = 0, j = i+1;
        while (j < nums.length) {
            if (nums[i] != 0) {
                i++;
                j++;
            }
            else {
                if (nums[j] == 0) j++;
                else {
                    swap(nums, i, j);
                    i++;
                }
            }
        }
    }
    public void swap(int[] nums, int i, int j) {
        int temp = nums[i];
        nums[i] = nums[j];
        nums[j] = temp;
    }
}
    

Update 2018-8

class Solution {
    public void moveZeroes(int[] nums) {
        if (nums == null || nums.length < 2) return;
        int i = 0, j = 1;
        while (j < nums.length) {
            if (nums[i] != 0) {
                i++;
                j++;
            } else {
                if (nums[j] == 0) {
                    j++;
                } else {
                    int temp = nums[i];
                    nums[i] = nums[j];
                    nums[j] = temp;
                    i++;
                }
            }
        }
    }
}