HDU 2136 Largest prime factor (prime number screening + playing table) __hdu

largest prime factor Time limit:5000/1000 MS (java/others) Memory limit:32768/32768 K (java/others)
Total submission (s): 9962 accepted Submission (s): 3514

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.
The position of Prime 2 is 1, Prime 3 are 2, and Prime 5 is 3, etc.
Specially, LPF (1) = 0.

Input each line would contain one integer n (0 < n < 1000000). Output output the LPF (n).

Sample Input

1 2 3 4 5 Sample Output

0 1 2 1 3
Author Wiskey
Source
AC Code:

#include <iostream>  
#include <memory.h>  
#include <cstdlib>  
#include <cstdio>  
#include <cmath>  
#include <cstring>  
#include <string>  
#include <cstdlib>  
#include <iomanip>  
#include <vector>  
#include <list>  
#include <map>  
#include <algorithm>  
typedef long LL;  
using namespace std; 
Const LL MAXN=1E6;
Const LL mod=10000000; 
int a[maxn]={0};
Prime number filter: Hit the table 
int main ()
{
	
	int n,k=1;
	for (int i=2;i<maxn;i++)
	{
		if (a[i]==0)
		{
			a[i]=k++,//position for 
			(int j=i+i;j<maxn; J+=i)
			{
				a[j]=a[i];
	}} while (~SCANF ("%d", &n))
	{
		if (n==1) printf ("0\n"); 
		else
		cout<<a[n]<<endl;
	}
    return 0;	
}