A perfect number is a positive integer that is equal to the sum of its positive divisors, excluding the number itself. A divisor of an integer x is an integer that can divide x evenly.
Given an integer n, return true if n is a perfect number, otherwise return false.
Example 1:
Input: num = 28
Output: true
Explanation: 28 = 1 + 2 + 4 + 7 + 14
1, 2, 4, 7, and 14 are all divisors of 28.
Example 2:
Input: num = 7
Output: false
Constraints:
-
1 <= num <= 108
SOLUTION:
class Solution:
def getFactors(self, n, factors):
for i in range(n - 1, 0, -1):
if i not in factors and n % i == 0:
factors.update({i})
factors.update({n//i})
self.getFactors(i, factors)
def checkPerfectNumber(self, num: int) -> bool:
fsum = 1
i = 2
while i * i <= num:
if num % i == 0:
fsum = fsum + i + num//i
i += 1
return (True if fsum == num and num!=1 else False)
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