POJ 1338 Ugly Numbers

Ugly Numbers

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 18395		Accepted: 8138

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
题目大意：如果一个数的质因子只有2，3，5则该数是一个丑数，输入n求第n个丑数。

#include <stdio.h>
#include <iostream>
using namespace std;

int main()
{
    int result[1505] = {0, 1};
    int n2 = 1, n3 = 1, n5 = 1, n;
    for (int i = 2; i <= 1500; i++)
    {
        result[i] = min(result[n2] * 2, min(result[n3] * 3, result[n5] * 5));
        if (result[i] == result[n2] * 2)
        {
            n2++;
        }
        if (result[i] == result[n3] * 3)
        {
            n3++;
        }
        if (result[i] == result[n5] * 5)
        {
            n5++;
        }
    }
    while(scanf("%d", &n) != EOF && n != 0)
    {
        printf("%d
", result[n]);
    }
    return 0;
}