[math][第二阶段-easy math][HDU-2136]Largest prime factor

Problem Description

Everybody knows any number can be combined by the prime number.
Now, your task is telling me what position of the largest prime factor.
The position of prime 2 is 1, prime 3 is 2, and prime 5 is 3, etc.
Specially, LPF(1) = 0.

 

Input

Each line will contain one integer n(0 < n < 1000000).

 

Output

Output the LPF(n).

 

Sample Input

12345

 

Sample Output

01213

 

import java.util.Scanner;public class Main {public static void main(String[] args) {// TODO Auto-generated method stubScanner in = new Scanner(System.in);int[] Prime = new int[1000010]; int sum = 0;  for(int i = 2; i <= 1000000; ++i)    if(Prime[i] == 0)    {      ++sum;      Prime[i] = sum;      for(int j = i+i; j <= 1000000; j+=i)        Prime[j] = sum;    }    while(in.hasNext()){  int n = in.nextInt();  System.out.println(Prime[n]);  }}}