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.
Solve it recursively ....
bool isUgly(int num) {
if(num<1)return false;
if(num==1) return true;
if(num%2==0) return isUgly(num/2);
else if(num%3==0) return isUgly(num/3);
else if(num%5==0) return isUgly(num/5);
else return false;
}