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# move-zeroes

## Problem Description

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.

## Solution

Two pointer (left, right), left keep track most left zero number position, right keep track of left most non-zero number position, then do swap(left, right). Continue the process until the end of array nums.
For example: Move Zeroes

### Complexity Analysis

Time Complexity: `O(N)`
Space Complexity: `O(1)`
• N - the length of array nums

### Code

class Solution {
public void moveZeroes(int[] nums) {
if (nums == null || nums.length < 2) return;
int l = 0;
int r = 1;
int len = nums.length;
while (l < len && r < len) {
// Find left most zero position
while (l < len && nums[l] != 0) {
l++;
}
if (r < l) {
r = l + 1;
}
// find left most non zero position
while (r < len && nums[r] == 0) {
r++;
}
// if out of array, break
if (r >= len) return;
// swap zero and non zero
swap(nums, l, r);
}
}
private void swap(int[] nums, int a, int b) {
int temp = nums[a];
nums[a] = nums[b];
nums[b] = temp;
}
}