HDU 5108 Alexandra and Prime Numbers

Alexandra and Prime Numbers

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 1019    Accepted Submission(s): 358

Problem Description

Alexandra has a little brother. He is new to programming. One day he is solving the following problem: Given an positive integer N, judge whether N is prime.
The problem above is quite easy, so Alexandra gave him a new task: Given a positive integer N, find the minimal positive integer M, such that N/M is prime. If such M doesn't exist, output 0.
Help him!

Input

There are multiple test cases (no more than 1,000). Each case contains only one positive integer N.
N≤1,000,000,000.
Number of cases with N>1,000,000

Output

For each case, output the requested M, or output 0 if no solution exists.

Sample Input

3 4 5 6

Sample Output

1 2 1 2

#include<iostream>
#include<stdio.h>
#include<math.h>
using namespace std;

int main()
{
  int n,i,ans,cnt;
  
  while(scanf("%d",&n)!=EOF)
  {
    if(n==1)
    {
      printf("0\n");
      continue;
    }
    ans=n;
    for(i=2;i*i<=n;i++)
    {
      if(n%i==0)//每次去除质因数 
      {
        while(n%i==0)
          n/=i; 
        cnt=i;//保存最大的质因数 
      } 
    }
    if(n>1)//若不是1，则剩余n为质数 ，否则被完全分解，除 
      cnt=n;
    printf("%d\n",ans/cnt);
  }   
  return 0;
}