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：

 1 #include <stdio.h>

 2 #include <string.h>

 3 #include <math.h>

 4 

 5 #define N   100000

 6 #define yes '1'

 7 #define no  '0'

 8 char flag[N+1];

 9 

10 void is_prime(int n)

11 {

12     int i, j;

13     memset(flag, yes, sizeof(flag));

14     flag[0]=flag[1]=no;

15     int len=sqrt(n)+1;

16     for(i=2; i<len; i++)

17     {

18         if(flag[i]==no) continue;

19         for(j=i+i; j<=n; j+=i)

20             flag[j]=no;

21     }

22 }

23 

24 int main(void)

25 {

26     int n;

27     ///find the primes from 1 to n(n<=N)

28     scanf("%d", &n);

29     is_prime(n);

30     for(int i=1; i<=n; i++)

31         if(flag[i]==yes)

32             printf("%8d", i);

33     printf("\n");

34     return 0;

35 }

 

解题：

 1 #include <stdio.h>

 2 #include <string.h>

 3 #include <math.h>

 4  

 5 #define N   100050

 6 #define yes '1'

 7 #define no  '0'

 8 char flag[N];

 9  

10 void is_prime(int n)

11 {

12     int i, j;

13     memset(flag, yes, sizeof(flag));

14     flag[0]=flag[1]=no;

15     int len=sqrt(n)+1;

16     for(i=2; i<len; i++)

17     {

18         if(flag[i]==no) continue;

19         for(j=i+i; j<=n; j+=i)

20             flag[j]=no;

21     }

22 }

23 

24 

25 

26 int main()

27 {

28     int n;

29     int count;

30     int t,i,k,num;

31     int max;

32     scanf("%d",&t);

33     while (t--) {

34         scanf("%d", &n);

35         max=0;

36         for (i=0;i<n;++i) {

37             count=0;

38             scanf("%d",&num);

39  

40             is_prime(num);

41             for(i=1; i<=num; i++)

42                 if(flag[i]==yes){

43                     if(num%i==0)

44                     count++;

45             }

46             if(count>max) 

47             {

48                 max=count;

49                 k=num;

50             }

51             if (count==max)

52             {

53                    if (k>num) k=num;

54             }

55         }

56         printf("%d\n",k);

57     }

58     return 0;

59 }

Winifred:

 1 #include <stdio.h>

 2 #include <string.h>

 3 bool f[100025];

 4 int T,p[100025];

 5 

 6 void getprime()

 7 {

 8     int i,j;

 9     memset(f,true,sizeof(f));

10     f[1]=false;

11     for (i=2;i<=100000;i++)

12     if (f[i])

13     {

14         for (j=i+i;j<=100000;j+=i) f[j]=false;

15     }

16     T=0;

17     for (i=2;i<=100000;i++)

18     if (f[i])

19     {

20         T++;

21         p[T]=i;

22     }

23 }

24 

25 int getdivnum(int x)

26 {

27     int ans=0,tmp=x;

28     for (int i=1;i<=T;i++)

29     {

30         if (tmp%p[i]==0)

31         {

32             ans++;

33             while (tmp%p[i]==0) tmp/=p[i];

34         }

35         if (p[i]>tmp) break;

36     }

37     return ans;

38 }

39 int main()

40 {

41     getprime();

42     int cas;

43     scanf("%d",&cas);

44     while (cas--)

45     {

46         int n;

47         scanf("%d",&n);

48         int Max=0,u;

49         for (int i=1;i<=n;i++)

50         {

51             int x;

52             scanf("%d",&x);

53             int t=getdivnum(x);

54             if (t>Max)

55             {

56                 Max=t;

57                 u=x;

58             }

59             else if (t==Max)

60             {

61                 if (u>x) u=x;

62             }

63         }

64         printf("%d\n",u);

65     }

66     getprime();

67 }