pku_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

1290

Sample Output

1210

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代码：

#include<iostream>using namespace std;int num[1501];int min(int a,int b,int c){if(c>a) c=a;if(c>b) c=b;return c;}void getNumList(){int i,j,k;int n;for(n=1;n<=5;++n) num[n]=n;for(i=3,j=2,k=2;n<=1500;++n) {num[n]=min(num[i]*2,num[j]*3,num[k]*5);while(num[i]*2<=num[n])++i;while(num[j]*3<=num[n])++j;while(num[k]*5<=num[n])++k;}}int main(){getNumList();int n;while(cin>>n && n) {cout<<num[n]<<endl;}return 0;} 

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PS:貌似不是什么难题，但是WA好几次居然将num[k]*5写成num[k]*4了，囧...