[Leetcode]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:

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

方法一：时间复杂度O(N^2)

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

方法二：时间复杂度O(N)

public class Solution {
    public void moveZeroes(int[] nums) {
        int newIndex = 0;
        
        for (int i = 0; i < nums.length ; i++) {
            if (nums[i] != 0) {
                nums[newIndex++] = nums[i];
            }
        }
        for (; newIndex < nums.length; newIndex++) {
            nums[newIndex] = 0;
        }
    }
}