Problem:
Write a program to check whether a given number is an ugly number.
Ugly numbers are positive numbers whose prime factors only include 2, 3, 5.
Example 1:
Input: 6
Output: true
Explanation: 6 = 2 × 3
Example 2:
Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2
Example 3:
Input: 14
Output: false
Explanation: 14 is not ugly since it includes another prime factor 7.
Note:
- 1 is typically treated as an ugly number.
- Input is within the 32-bit signed integer range: ([−2^{31}, 2^{31} − 1]).
思路:
Solution (C++):
bool isUgly(int num) {
if (num <= 0) return false;
while (num % 2 == 0) num /= 2;
while (num % 3 == 0) num /= 3;
while (num % 5 == 0) num /= 5;
if (num == 1) return true;
return false;
}
性能:
Runtime: 0 ms Memory Usage: 5.9 MB
思路:
Solution (C++):
性能:
Runtime: ms Memory Usage: MB