hdoj Max Factor

Max Factor

Time Limit : 2000/1000ms (Java/Other)   Memory Limit : 32768/32768K (Java/Other)Total Submission(s) : 20   Accepted Submission(s) : 9

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Problem Description

To improve the organization of his farm, Farmer John labels each of his N (1 <= N <= 5,000) cows with a distinct serial number in the range 1..20,000. Unfortunately, he is unaware that the cows interpret some serial numbers as better than others.In particular, a cow whose serial number has the highest prime factor enjoys the highest social standing among all the other cows.(Recall that a prime number is just a number that has no divisors except for 1 and itself. The number 7 is prime while the number 6, being divisible by 2 and 3, is not).Given a set of N (1 <= N <= 5,000) serial numbers in the range 1..20,000, determine the one that has the largest prime factor.

Input

* Line 1: A single integer, N* Lines 2..N+1: The serial numbers to be tested, one per line

Output

* Line 1: The integer with the largest prime factor. If there are more than one, output the one that appears earliest in the input file.

Sample Input

4
36
38
40
42

Sample Output

38

#include<cstdio>#include<cstdlib>#include<cstring>#define maxn 30000using namespace std;int  isprime[maxn];void   countprime(){       int i,j;       for(i=2;i*i<maxn;++i){       if(isprime[i])continue;       for(j=i*i;j<maxn;j+=i)       isprime[j]=1;}       }int main(){    countprime();    int a,n,k,i,j,max;    while(scanf("%d",&k)!=EOF){                               max=0;    while(k--){    scanf("%d",&n);    for(i=n;i>=0;--i){    if((n%i==0)&&(isprime[i]!=1))break;    }    if(i>max){    max=i;a=n;}    }    printf("%d\n",a);    }    return 0;    }