# 1304.Find-N-Unique-Integers-Sum-up-to-Zero

## 1304. Find N Unique Integers Sum up to Zero

## 题目地址

<https://leetcode.com/problems/find-n-unique-integers-sum-up-to-zero/>

## 题目描述

```
Given an integer n, return any array containing n unique integers such that they add up to 0.

Example 1:
Input: n = 5
Output: [-7,-1,1,3,4]
Explanation: These arrays also are accepted [-5,-1,1,2,3] , [-3,-1,2,-2,4].

Example 2:
Input: n = 3
Output: [-1,0,1]

Example 3:
Input: n = 1
Output: [0]

Constraints:
1 <= n <= 1000
```

## 代码

### Approach #1

`A[i] = i * 2 - n + 1`

```java
class Solution {
  public int[] sumZero(int n) {
        int[] A = new int[n];
    for (int i = 0; i < n; i++) {
      A[i] = i * 2 - n + 1;
    }

    return A;
  }
}
```

### Approach #2 Two Points

```java
public int[] sumZero(int n) {
    int[] res = new int[n];
    int left = 0, right = n - 1, start = 1;
    while (left < right) { // in the middle is zero
        res[left++] = start;
        res[right--] = -start;
        start++;
    }
    return res;
  }
```