poj_1338_UglyNumbers.cpp

Problem Links:

poj1338, UVa00136,

Problem:

Ugly Numbers

Time Limit: 1000MS		Memory Limit: 10000K
Total Submissions: 13375		Accepted: 5897

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

Solution:

The alternative way is just print out the answer: 859963392.

Source Code:

#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;
    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\n",r[i]);
        scanf("%d",&i);
    }
    return 0;
}