507 Perfect Number

1. Description

A perfect number is a positive integer that is equal to the sum of positive divisors, excluding the number of 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.

 

constraints :

• 1 <= num <= \(10^{8}\)

2. Algorithms

1. Start
2. If num is 1, return False
3. Declare variable named sum_ and initialize it to 1.
4. Repeat the steps through integers range 2 - int(sqrt(num)) + 1.
   1. If i is divisor of num, increment sum_ by (i + num/i).
5. Return True if sum_ is same with num.
6. End

 

3. Codes

class Solution:
    def checkPerfectNumber(self, num: int) -> bool:
        if num == 1 : return False 
        sum_ = 1
        for i in range(2, int(math.sqrt(num)) + 1) : 
            if num % i == 0: 
                sum_ += (i + num/i)
        
        return sum_ == num

 

4. Conclusion