Leetcode_263_Ugly Number

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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. For example, 6, 8 are ugly while 14 is not ugly since it includes another prime factor 7.

Note that 1 is typically treated as an ugly number.

思路：

（1）该题题意为给定一个数，判断该数是否为“丑数”。

（2）这道题很基础。丑数是因子只含有2、3、5的数。所以只需对这三个数循环取余判断即可。这里不再累赘。

（3）详情见下方代码。希望本文对你有所帮助。

public class Ugly_Number {

	public static void main(String[] args) {
		for (int i = 0; i < 100; i++) {
			System.err.println(i + "==" + isUgly(i));
		}
	}

	// 2 3 5
	public static boolean isUgly(int num) {

		if (num == 1)
			return true;

		while (num >= 2 && num % 2 == 0) {
			num = num / 2;
		}

		while (num >= 3 && num % 3 == 0) {
			num = num / 3;
		}

		while (num >= 5 && num % 5 == 0) {
			num = num / 5;
		}

		return num == 1 ? true : false;
	}

}