POJ 1338 Ugly Numbers

 

Description

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, ... 
shows the first 10 ugly numbers. By convention, 1 is included. 
Given the integer n,write a program to find and print the n'th ugly number. 

Input

Each line of the input contains a postisive integer n (n <= 1500).Input is terminated by a line with n=0.

Output

For each line, output the n’th ugly number .:Don’t deal with the line with n=0.

Sample Input

1
2
9
0

Sample Output

1
2
10

#include<stdio.h>
int ugly[1505];

int min(int a,int b)
{
    return a>b?b:a;
}
int main()
{
    int p2,p3,p5;
    int i,in;
    p2=0,p3=0,p5=0;
    ugly[0]=1;
    for(i=1;i<1500;i++)
    {
        ugly[i]=min(min(ugly[p2]*2,ugly[p3]*3),ugly[p5]*5);
        if(ugly[i]==ugly[p2]*2) p2++;
        if(ugly[i]==ugly[p3]*3) p3++;
        if(ugly[i]==ugly[p5]*5) p5++;
    }
    //printf("%d %d %d",p2,p3,p5);
    while(scanf("%d",&in)&&in!=0)
    {
        printf("%d/n",ugly[in-1]);
    }
    return 0;
}