LeetCode: 283. Move Zeroes

LeetCode: 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.

For example, given nums = [0, 1, 0, 3, 12], after calling your
function, nums should be [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. Credits: Special thanks to
@jianchao.li.fighter for adding this problem and creating all test
cases.

自己的答案：

public class Solution {    public void moveZeroes(int[] nums) {        if (nums == null) {            return;        }        int left = -1;        for (int i = 0; i < nums.length; i++) {            if (nums[i] == 0) {                if (left < 0) {                    left = i;                }            } else {                if (left >= 0) {                    nums[left] = nums[i];                    nums[i] = 0;                    left++;                }            }        }    }}

O(N)的答案：

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;    }}