hdu 2710 Max Factor

Max Factor

Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 3109    Accepted Submission(s): 989

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

436384042

Sample Output

38

 

水题 不说什么了

 

 

#include<iostream>using namespace std;int ss[20050];int maxx;int main(){int i,k,j,n,temp;memset(ss,0,sizeof(ss));for(k=2;k<20001;k+=2)   ss[k]=2;ss[1]=1;for(i=3;i<20001;i+=2){if(!ss[i]){for(j=i;j<20001;j+=i)ss[j]=i;}}while(cin>>n){maxx=0;for(i=0;i<n;i++){cin>>temp;if(ss[temp]>ss[maxx]) maxx=temp;}cout<<maxx<<endl;}return 0;}