LeetCode //C - 1304. Find N Unique Integers Sum up to Zero

1304. Find N Unique Integers Sum up to Zero

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

From: LeetCode

Link: 1304. Find N Unique Integers Sum up to Zero

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Solution:

Ideas:

Pair each positive integer i with -i, and if n is odd, include 0.

Code:

/**
 * Note: The returned array must be malloced, assume caller calls free().
 */
int* sumZero(int n, int* returnSize) {
    *returnSize = n;
    int *ans = (int *)malloc(n * sizeof(int));
    
    int idx = 0;
    for (int i = 1; i <= n / 2; i++) {
        ans[idx++] = i;
        ans[idx++] = -i;
    }
    
    if (n % 2 == 1)
        ans[idx] = 0;
    
    return ans;
}