SZU:A25 Favorite Number

Judge Info

• Memory Limit: 32768KB
• Case Time Limit: 10000MS
• Time Limit: 10000MS
• Judger: Number Only Judger

Description

Frog Frank likes 30 more than likes 40, yet he likes 12 and 39 equally. This is because he likes numbers that have a lot of different prime factors. For example, 30 have 3 prime factors (2,3 and 5) and 40 have 2(2 and 5) only. A prime number is a number that can be divided evenly only by itself and 1.

Task

You are given a list of numbers, find out which of the numbers Frank likes most. If there are more than one solutions, output the smallest.

Input

The first line of input contains , the number of test cases. First line of each test case contains a integers . The following line contains N positive integers, all of them are not greater than 100, 000.

Output

For each test case, print a line contains the solution.

Sample Input

2
10
3 5 7 9 11 13 15 17 19 21
11
2 4 6 8 10 13 39 105 200 201 143

Sample Output

15
105
 
解题思路：素数筛选
 
算法 from dd：

 #include <stdio.h>
 #include <string.h>
 #include <math.h>
 
 #define N   100000
 #define yes '1'
 #define no  '0'
 char flag[N+];
 
 void is_prime(int n)
 {
     int i, j;
     memset(flag, yes, sizeof(flag));
     flag[]=flag[]=no;
     int len=sqrt(n)+;
     for(i=; i<len; i++)
     {
         if(flag[i]==no) continue;
         for(j=i+i; j<=n; j+=i)
             flag[j]=no;
     }
 }
 
 int main(void)
 {
     int n;
     ///find the primes from 1 to n(n<=N)
     scanf("%d", &n);
     is_prime(n);
     for(int i=; i<=n; i++)
         if(flag[i]==yes)
             printf("%8d", i);
     printf("\n");
     return ;
 }

解题：

 #include <stdio.h>
 #include <string.h>
 #include <math.h>
 
 #define N   100050
 #define yes '1'
 #define no  '0'
 char flag[N];
 
 void is_prime(int n)
 {
     int i, j;
     memset(flag, yes, sizeof(flag));
     flag[]=flag[]=no;
     int len=sqrt(n)+;
     for(i=; i<len; i++)
     {
         if(flag[i]==no) continue;
         for(j=i+i; j<=n; j+=i)
             flag[j]=no;
     }
 }
 
 int main()
 {
     int n;
     int count;
     int t,i,k,num;
     int max;
     scanf("%d",&t);
     while (t--) {
         scanf("%d", &n);
         max=;
         for (i=;i<n;++i) {
             count=;
             scanf("%d",&num);
 
             is_prime(num);
             for(i=; i<=num; i++)
                 if(flag[i]==yes){
                     if(num%i==)
                     count++;
             }
             if(count>max)
             {
                 max=count;
                 k=num;
             }
             if (count==max)
             {
                    if (k>num) k=num;
             }
         }
         printf("%d\n",k);
     }
     return ;
 }

Winifred:

 #include <stdio.h>
 #include <string.h>
 bool f[];
 int T,p[];
 
 void getprime()
 {
     int i,j;
     memset(f,true,sizeof(f));
     f[]=false;
     for (i=;i<=;i++)
     if (f[i])
     {
         for (j=i+i;j<=;j+=i) f[j]=false;
     }
     T=;
     for (i=;i<=;i++)
     if (f[i])
     {
         T++;
         p[T]=i;
     }
 }
 
 int getdivnum(int x)
 {
     int ans=,tmp=x;
     for (int i=;i<=T;i++)
     {
         if (tmp%p[i]==)
         {
             ans++;
             while (tmp%p[i]==) tmp/=p[i];
         }
         if (p[i]>tmp) break;
     }
     return ans;
 }
 int main()
 {
     getprime();
     int cas;
     scanf("%d",&cas);
     while (cas--)
     {
         int n;
         scanf("%d",&n);
         int Max=,u;
         for (int i=;i<=n;i++)
         {
             int x;
             scanf("%d",&x);
             int t=getdivnum(x);
             if (t>Max)
             {
                 Max=t;
                 u=x;
             }
             else if (t==Max)
             {
                 if (u>x) u=x;
             }
         }
         printf("%d\n",u);
     }
     getprime();
 }