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:

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

Credits:
Special thanks to @jianchao.li.fighter for adding this problem and creating all test cases.

思路： 使用一个索引，指向将要替换数字的位置， 若值非空，则将该值赋值到索引所在的位置，并将索引往后移位。

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
     
    int j=0;
    for(int val:nums)
    {
       if(val!=0)
          nums[j++]=val;
    }
    for(;i<nums.size();j++)
       nums[j]=0;
    }
};