[LeetCode][JavaScript]Move Zeroes

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.

https://leetcode.com/problems/move-zeroes/

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把数组中所有的零放到最后，不能简单地再开一个数组。

第一种优雅的做法，开一个变量count=0，把数组中不为零的数，按顺序移动到下标为count的位置上，每移动一个count++，最后补上0。

/**
 * @param {number[]} nums
 * @return {void} Do not return anything, modify nums in-place instead.
 */
var moveZeroes = function(nums) {
    var count = 0;
    for(var i = 0; i < nums.length; i++){
        if(nums[i] !== 0){
            nums[count] = nums[i];
            count++;
        }
    }
    for(; count < nums.length ; count++){
        nums[count] = 0;
    }  
};

第二种调用了强大的splice方法，先记录下0的位置，从后往前把0从数组中删掉（从前往后会打乱下标的顺序），最后再补齐。

/**
 * @param {number[]} nums
 * @return {void} Do not return anything, modify nums in-place instead.
 */
var moveZeroes = function(nums) {
    var indexArr = [], i;
    for(i = 0; i < nums.length; i++){
        if(nums[i] === 0){
            indexArr.push(i);
        }
    }
    for(i = indexArr.length - 1; i >= 0; i--){
        nums.splice(indexArr[i], 1);
    }
    for(i = 0; i < indexArr.length; i++){
        nums.push(0);
    }
};