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.
public class Solution {
public boolean isUgly(int num) {
if(num<1)
return false;
else{
while(num>1){
if(num%2==0) num/=2;
else if(num%3==0) num/=3;
else if(num%5==0) num/=5;
else return false;
}
return true;
}
}
}
public class Solution {
public boolean isUgly(int num) {
while (num >= 2) {
if (num % 2 == 0) num /= 2;
else if (num % 3 == 0) num /= 3;
else if (num % 5 == 0) num /= 5;
else return false;
}
return num == 1; //这个判断好巧妙啊,涵盖了我上边的num<1的情况
}
}