2485. Find the Pivot Integer

Given a positive integer n, find the pivot integer x such that:

• The sum of all elements between 1 and x inclusively equals the sum of all elements between x and n inclusively.

Return the pivot integer x. If no such integer exists, return -1. It is guaranteed that there will be at most one pivot index for the given input.

class Solution {
public:
    int pivotInteger(int n) {
        int total = n * (n + 1) / 2, sum = 0;
        for(int i = 1; i <= n; i++) {
            sum += i;
            if(sum == total) return i;
            total -= i;
        }
        return -1;
    }
};