find_pivot_integer.py (791B)
| # 2485. Find the Pivot Integer
from math import sqrt
"""
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(object):
def pivotInteger(self, n):
"""
:type n: int
:rtype: int
"""
tmp = (n * n + n) // 2
sqr = int(sqrt(tmp))
if sqr * sqr == tmp:
return sqr
return -1
if __name__ == "__main__":
obj = Solution()
print(obj.pivotInteger(8))
print(obj.pivotInteger(1))
print(obj.pivotInteger(4))
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