LC-2485 Easy LeetCode

2485. Find the Pivot Integer

Read the full problem statement on LeetCode.

Difficulty: easy Acceptance: 84% Topics: Math, Prefix Sum

Reading material

Math & Geometry 12 min Prefix Sums & Difference Arrays 11 min

Reference solution (spoiler · python)

# Time:  O(1)
# Space: O(1)

# math
class Solution(object):
    def pivotInteger(self, n):
        """
        :type n: int
        :rtype: int
        """
        x = int(((n+1)*n//2)**0.5+0.5)
        return x if x**2 == (n+1)*n//2 else -1

Solution from kamyu104/LeetCode-Solutions · MIT