507. Perfect Number

Problem Statement

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:

Rust

impl Solution {
    pub fn check_perfect_number(num: i32) -> bool {
        if num == 1 {
            return false;
        }

        let (mut sum, mut i) = (1, 2);

        while i * i <= num {
            // if i is a factor of num, add i and num / i to sum
            if num % i == 0 {
                sum += i;
                if i * i != num {
                    sum += num / i;
                }
            }
            i += 1;
        }

        sum == num
    }
}

507. Perfect Number #

Problem Statement #

Solution: #

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507. Perfect Number

Problem Statement

Solution:

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