poj 1338 Ugly Numbers

Ugly Numbers

Time Limit: 1000MS Memory Limit: 10000KTotal Submissions: 21315 Accepted: 9520

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

Source

New Zealand 1990 Division I,UVA 136

#include<iostream>#include<cstdio>#include<cstring>#include<cmath>#include<string>#include<algorithm>#include<cstdlib>#include<set>#include<queue>#include<stack>#include<vector>#include<map>#define N 1510#define Mod 10000007#define lson l,mid,idx<<1#define rson mid+1,r,idx<<1|1#define lc idx<<1#define rc idx<<1|1const double EPS = 1e-11;const double PI = acos ( -1.0 );const double E = 2.718281828;typedef long long ll;const int INF = 1000010;using namespace std;int n;int num[1515];void init() {    int n2=1,n3=1,n5=1;    num[1]=1;    for(int i=2; i<=N; i++) {        num[i]=min(num[n2]*2,min(num[n3]*3,num[n5]*5));        if(num[i]==num[n2]*2)n2++;        if(num[i]==num[n3]*3)n3++;        if(num[i]==num[n5]*5)n5++;    }}int main() {    init();    while(~scanf("%d",&n)&&n)        printf("%d\n",num[n]);}