263_Ugly_Number_Easy.c

/*
 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. 
*/
//解法一 6ms
int fun(int num)
{
    if(num%2==0)
        num=num/2;
    else if(num%3==0)
        num=num/3;
    else if(num%5==0)
        num=num/5;
    if(num%2==0||num%3==0||num%5==0)
       num = fun(num);
    
    if(num==1)
        return 1;

    return 0;
}
bool isUgly(int num) {
    int i;
    int k;
    if(num<=0)
        return false;
    if(num==1)
        return true;
    k=fun(num);
    if(k==1)
        return true;
    else
        return false;
    return;
}

//解法二 3ms
bool isUgly(int num) {
    int i;
    for(i=2;i<6&&num;i++)
        while(num%i==0)
            num/=i;
    if(num==1)
        return true;
    else
        return false;
}