Leetcode Note: Go - Perfect Number

Perfect Number - LeetCode
https://leetcode.com/problems/perfect-number/

• Go 言語で取り組んだメモ

所感

• int が渡されるので perfect number か判定して bool を return する
• Perfect number - Wikipedia
• 完全数 - Wikipedia

回答

Perfect Number - LeetCode
https://leetcode.com/problems/perfect-number/solution/

Golang simple iterative solution, O(logN) - LeetCode Discuss
https://leetcode.com/problems/perfect-number/discuss/112194/Golang-simple-iterative-solution-O(logN)

func checkPerfectNumber(num int) bool {
	if num <= 1 {
		return false
	}
	sum := 0
	for i := 1; i*i <= num; i++ {
		if num%i == 0 {
			sum = sum + i + (num / i)
		}
	}
	return sum-num == num
}

• i * i <= num を条件にループ
  • num を i で割り切れるなら sum を更新
    • sum = sum + i + (num / i)
• sum-num == num で bool を return