notes/OJ notes/pages/Leetcode Move-Zeroes.md

# Leetcode Move-Zeroes

#### 2022-07-11 09:55

> ##### Algorithms:
>
> #algorithm #two_pointers #array_in_place_operation
>
> ##### Data structures:
>
> #DS #array
>
> ##### Difficulty:
>
> #coding_problem #difficulty_easy
>
> ##### Additional tags:
>
> #leetcode
>
> ##### Revisions:
>
> N/A

##### Related topics:

##### Links:

- [Link to problem](https://leetcode.com/problems/move-zeroes/)

---

### Problem

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.

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

#### Examples

**Example 1:**

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

**Example 2:**

**Input:** nums = [0]
**Output:** [0]

#### Constraints

**Constraints:**

- `1 <= nums.length <= 104`
- `-231 <= nums[i] <= 231 - 1`

### Thoughts

> [!summary]
> This is a #array_in_place_operation problem.

Because the data can be overwritten, and zeros can be predicted in the result array, I use in-place array operations.

### Solution

```cpp
class Solution {
public:
  void moveZeroes(vector<int> &nums) {
    // Tow pointers, since data can be overwritten and one pointer is faster
    // than another.
    int num = 0;

    for (int i = 0; i < nums.size(); i++) {
      if (nums[i] != 0) {
        nums[num++] = nums[i];
      }
    }

    for (int j = num; j < nums.size(); j++) {
      nums[j] = 0;
    }
  }
};
```