Largest prime factor

Time Limit: 5000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 17192    Accepted Submission(s): 5977
 

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

1 2 3 4 5

Sample Output

0 1 2 1 3

Author

Wiskey

Source

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題目分析：

              求一個數的最大質因子的位置。所以要用打表法來做！

程式碼如下：

#include<iostream>
#define maxn 1000001

using namespace std;

int prime[maxn];

void prepare()
{
	
	int k=1;
	for(int i=2;i<maxn;i++)
	{
		if(prime[i]==0)
		{
			for(int j=1;j*i<maxn;j++)
				prime[j*i]=k;
			k++;
		}
	}
	
}

int main()
{
	prepare();
	int T;
	while(~scanf("%d",&T))
	{
		printf("%d\n",prime[T]);
	}
	
	return 0;
}