Watch 10 video solutions for Find the Pivot Integer, a easy level problem involving Math, Prefix Sum. This walkthrough by NeetCode has 63,567 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
Given a positive integer n, find the pivot integer x such that:
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.
Example 1:
Input: n = 8 Output: 6 Explanation: 6 is the pivot integer since: 1 + 2 + 3 + 4 + 5 + 6 = 6 + 7 + 8 = 21.
Example 2:
Input: n = 1 Output: 1 Explanation: 1 is the pivot integer since: 1 = 1.
Example 3:
Input: n = 4 Output: -1 Explanation: It can be proved that no such integer exist.
Constraints:
1 <= n <= 1000