LeetCode #283 - Move Zeroes

题目描述：

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.

定义两个指针，i每次移动一步，j每次都向后遍历，直到指向非0的数，那么这两个指针交换。在j>i时，nums[i]必定为0，因为非0的数都被j遍历过，所以两个指针交换可以令所有的0逐渐移到数组后面。

class Solution {
public:
    void moveZeroes(vector<int>& nums) {
        int i=0;
        int j=0;
        while(i<nums.size())
        {
           if(nums[i]==0) i++;
           else
           {
               swap(nums[i],nums[j]);
               i++;
               j++;
           }
        }
    }
};