hdu 5108 Alexandra and Prime Numbers

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <algorithm>
 4 #define ll long long
 5 #define N 100000
 6 using namespace std;
 7 
 8 ll n;
 9 
10 
11 int main()
12 {
13     while(scanf("%lld",&n)!=EOF)
14     {
15         ll m=n;
16         if(n==1)
17         {
18             printf("0\n");
19             continue;
20         }
21         bool flag=false;
22         for(int i=2; i*i<=n; i++)
23         {
24             if(n%i==0)
25             {
26                 flag=true;
27                 break;
28             }
29         }
30         if(!flag)
31         {
32             printf("1\n");
33             continue;
34         }
35         ll max1=2;
36         for(int i=2; i*i<=n; i++)
37         {
38             if(n%i==0)
39             {
40                  if(max1<i) max1=i;
41                  while(n%i==0) n/=i;
42             }
43         }
44         if(n>1)
45         {
46             if(max1<n)
47             {
48                 max1=n;
49             }
50         }
51         printf("%lld\n",m/max1);
52     }
53     return 0;
54 }