[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.

思路：

首先扫描一遍数组统计0个数，然后将非0元素从起始位置开始往后排。

two pointer的思想。

void moveZeroes(vector<int>& nums)
     {
         int zeros = 0;
         for (int i = 0; i < nums.size();i++)
         {
             if (nums[i] == 0) zeros++;
         }
         int first = 0;
         for (int i = 0; i < nums.size();i++)
         {
             if (nums[i] != 0)
             {
                 nums[first++] = nums[i];
             }
         }
         for (int i =first; i < nums.size();i++)
         {
             nums[i] = 0;
         }
     }