283. Move Zeroes

 283. Move Zeroes  (https://leetcode.com/problems/move-zeroes/)

Given an integer array nums, move all 0's to the end of it while maintaining the relative order of the non-zero elements.

Note that you must do this in-place without making a copy of the array.

Example 1:
Input: nums = [0,1,0,3,12]
Output: [1,3,12,0,0]

Example 2:
Input: nums = [0]
Output: [0]
 
Constraints:
1 <= nums.length <= 10^4
-2^31 <= nums[i] <= 2^31 - 1

 

Follow up: Could you minimize the total number of operations done?

用雙指標
快指標去找出所有非零的元素
逐一的排列到慢指標的位置
最後再從慢指標的位置，把之後的所有元素都設為零
這樣就可以依序保存所有非零的元素
並且把零都挪到陣列末端

class Solution {

public:

    void moveZeroes(vector<int>& nums) {

        if (nums.size() == 1)

            return;

        int i = 0;

        int j = 0;

        while (j < nums.size())

        {

            if (nums[j] != 0)

            {

                nums[i] = nums[j];

                i++;

            }

            j++;

        }

        while(i < nums.size())

        {

            nums[i] = 0;

            i++;

        }

    }

};

參考: https://www.youtube.com/watch?v=vy9QG75U77g&list=PLY_qIufNHc29OLToHki4t0Z5KIhUzdYxD&index=4