【HDU 2161】Primes（素数~水）



Primes

Time Limit: 1000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 11937    Accepted Submission(s): 4939

Problem Description

Write a program to read in a list of integers and determine whether or not each number is prime. A number, n, is prime if its only divisors are 1 and n. For this problem, the numbers 1 and 2 are not considered primes.

 

Input

Each input line contains a single integer. The list of integers is terminated with a number<= 0. You may assume that the input contains at most 250 numbers and each number is less than or equal to 16000.

 

Output

The output should consists of one line for every number, where each line first lists the problem number, followed by a colon and space, followed by "yes" or "no".

 

Sample Input

12345170

 

Sample Output

1: no2: no3: yes4: no5: yes6: yes
思路：注意是 n<=0 时 break，不看题wa了两发……
#include<bits/stdc++.h>#define manx 16123using namespace std;bool a[manx];void prime(){    memset(a,true,sizeof(a));    for (int i=2; i<manx; i++){        if(a[i]){            for (int j=i+i; j<manx; j+=i)                a[j]=false;        }    }    a[0]=false; a[1]=false; a[2]=false;}void solve(){    int n,cas=1;    while(~scanf("%d",&n)){        if(n<=0) break;        printf("%d: ",cas++);        if(a[n]) printf("yes\n");        else printf("no\n");    }}int main(){    prime();    solve();    return 0;}