Ugly Numbers（丑数）

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 <iostream>#include <string.h>#include <cstdio>#include <algorithm>#include <string>using namespace std;long long min(long long a,long long  b,long long c){ long long x=a<b?a:b;  return x<c?x:c;}int main(){ long long num[1505]; long long p2,p3,p5;  p2=p3=p5=1;  memset(num,0,sizeof(num));  num[1]=1;  int i=1;  while(i<=1501){    num[++i]=min(num[p2]*2,num[p3]*3,num[p5]*5);if(num[i]==num[p2]*2) p2++;if(num[i]==num[p3]*3) p3++;if(num[i]==num[p5]*5) p5++;  }  int n;  while(scanf("%d",&n)&&n){printf("%lld
",num[n]);  }  return 0;}