Ugly Numbers Program

Ugly numbers are numbers whose only prime factors are 2, 3 or 5. The sequence
1, 2, 3, 4, 5, 6, 8, 9, 10, 12, 15, …
shows the first 11 ugly numbers. By convention, 1 is included.
Write a program to find and print the 150’th ugly number.

# include
# include
 
/*This function divides a by greatest divisible 
  power of b*/
int maxDivide(int a, int b)
{
  while (a%b == 0)
   a = a/b; 
  return a;
}   
 
/* Function to check if a number is ugly or not */
int isUgly(int no)
{
  no = maxDivide(no, 2);
  no = maxDivide(no, 3);
  no = maxDivide(no, 5);
   
  return (no == 1)? 1 : 0;
}    
 
/* Function to get the nth ugly number*/
int getNthUglyNo(int n)
{
  int i = 1; 
  int count = 1;   /* ugly number count */
 
  /*Check for all integers untill ugly count 
    becomes n*/
  while (n > count)
  {
    i++;      
    if (isUgly(i))
      count++; 
  }
  return i;
}
 
/* Driver program to test above functions */
int main()
{
    unsigned no = getNthUglyNo(150);
    printf("150th ugly no. is %d ",  no);
    getchar();
    return 0;
}

This method is not time efficient as it checks for all integers until ugly number count becomes n, but space complexity of this method is O(1)

Methods to use involve dynamic programming, google it