# Move Zeroes

Easy

## Question

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
a) You must do this in-place without making a copy of the array.
b) 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].

## Thinking

• 0 always be moved to the last position
• Shift all elements
• Make sure to check current element again.

## Review

• Using Two Pointers

## Solution

#### Java (Two pointers)

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

}
}

#### Java (Two for loop. Not good)

public class Solution {
/**
* @param nums an integer array
* @return nothing, do this in-place
*/
public void moveZeroes(int[] nums) {
if (nums == null) {
return;
}
int zeroCount = 0;
for (int i = 0; i < nums.length; i++) {
if ((i + zeroCount) == nums.length) {
break;
}
if (nums[i] == 0) {
for (int j = i; j < nums.length - 1; j++) {
nums[j] = nums[j + 1];
}
nums[nums.length - 1] = 0;
zeroCount++;
i--; // check current element again
}
}
}
}