05 August 2008
Write a program to check whether a given number is an ugly number.
Ugly numbers are positive numbers whose prime factors only include 1
2, 3, 5
Example 1:
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Input: 6
Output: true
Explanation: 6 = 2 × 3
Example 2:
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Input: 8
Output: true
Explanation: 8 = 2 × 2 × 2
Example 3:
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Input: 14
Output: false
Explanation: 14 is not ugly since it includes another prime factor 7.
Note:
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看给定的一个数是否是正整数并且是否只包含2， 3，5这三个因子，做法就是遍历2，3，5，如果可以整除就逮住一直除，最后判断是否为1，如果除到最后不为1就说明还有别的因子，不是丑数。
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class Solution {
public boolean isUgly(int num) {
if (num <= 0) {
return false;
}
int[] divisions = new int[]{2, 3, 5};
for (int division : divisions) {
while (num % division == 0) {
num /= division;
}
}
return num == 1;
}
}