【杭电-oj】-2138-How many prime numberszz

How many prime numbers

Time Limit: 3000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 15847    Accepted Submission(s): 5491

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

 

注意数据开根号的使用！还有只要有一次可以整除即退出，减少时间。

#include<cstdio>#include<cmath>int a[1000011]={1,1};int main(){int t;while(~scanf("%d",&t)){int y=0;for(int j=1;j<=t;j++){int m,k;int x=0;scanf("%d",&m);if(m==2)y++;else{k=sqrt(m);for(int i=2;i<=k;i++){if(m%i==0){x++;break;}}if(x==0)y++;}}printf("%d\n",y);} return 0;}