507. Perfect Number
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 = 6 Output: true
Example 3:
Input: num = 496 Output: true
Example 4:
Input: num = 8128 Output: true
Example 5:
Input: num = 2 Output: false
Constraints:
1 <= num <= 108
Rust Solution
struct Solution;
impl Solution {
fn check_perfect_number(num: i32) -> bool {
if num == 1 {
return false;
}
let mut i = 2;
let mut sum = 1;
while i * i <= num {
if num % i == 0 {
sum += i;
sum += num / i;
}
i += 1;
}
sum == num
}
}
#[test]
fn test() {
assert_eq!(Solution::check_perfect_number(28), true);
}
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