hdu 2138 How many prime numbers （Miller Rabbin大质数判定）

How many prime numbers

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 18144    Accepted Submission(s): 6180

Problem Description

  Give you a lot of positive integers, just to find out how many prime numbers there are.

 

Input

  There are a lot of cases. In each case, there is an integer N representing the number of integers to find. Each integer won’t exceed 32-bit signed integer, and each of them won’t be less than 2.

 

Output

  For each case, print the number of prime numbers you have found out.

 

Sample Input

32 3 4

 

Sample Output

2

 

Author

wangye

 

Source

HDU 2007-11 Programming Contest_WarmUp

 

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题解：Miller Rabbin大质数判定

控制一下尝试的次数，此题容易TLE

#include<iostream>#include<cstdio>#include<cstring>#include<algorithm>#include<cmath>#define LL long longusing namespace std;int n;LL quickpow(LL num,LL x,LL p){LL base=num%p; LL ans=1;while (x) {if (x&1) ans=ans*base%p;x>>=1;base=base*base%p;}return ans; }bool miller_rabbin(LL n){if (n==2) return true;if (n<2||!(n&1)) return false;LL t=0;LL a,x,y,u=n-1;while (!(u&1)) t++,u>>=1;for (int i=0;i<=100;i++) {a=rand()*rand()%(n-1)+1;x=quickpow(a,u,n);for (int j=0;j<t;j++) {y=x*x%n;if (y==1&&x!=1&&x!=n-1) return false;x=y;}if (x!=1) return false;} return true;}int main(){freopen("a.in","r",stdin);freopen("my.out","w",stdout);while (scanf("%d",&n)!=EOF){    int cnt=0;for (int i=1;i<=n;i++) {int x; scanf("%d",&x);cnt+=miller_rabbin((LL)x);} printf("%d\n",cnt);    }}