problem 1338: ugly numbers

Ugly Numbers
Time Limit:1000MS  Memory Limit:10000K
Total Submit:2558 Accepted:1121

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

Source
New Zealand 1990 Division I,UVA 136

my solution:

Source

Problem Id: 1338   User Id:keepRunning 
Memory:32K  Time:0MS
Language:C  Result:Accepted

Source 

#include < stdio.h >

int  r[ 1501 ];
int  Min( int  a, int  b, int  c) ... {
    if(a<b)b=a;
    if(b<c)c=b;
    return c;
}     
int  main() ... {
    int a;
    int b;
    int c;
    int i;
    int j;
    
    r[1]=1;r[2]=2;r[3]=3;r[4]=4;r[5]=5;
    a=3; b=2;  c=2;  
    for(i=6;i<=1500;i++)...{
        r[i]=Min(r[a]*2,r[b]*3,r[c]*5);
        for(;r[a]*2<=r[i];a++);
        for(;r[b]*3<=r[i];b++);
        for(;r[c]*5<=r[i];c++);
    }
    scanf("%d",&i);
    while(i)...{
        printf("%d ",r[i]);
        scanf("%d",&i);
    }
    return 0;
}