Primes
Time Limit: 1000/1000 MS (Java/Others) Memory Limit: 32768/32768 K (Java/Others)
Total Submission(s): 8959 Accepted Submission(s): 3754
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
1 2 3 4 5 17 0
Sample Output
1: no 2: no 3: yes 4: no 5: yes 6: yes
Source
2008 “Sunline Cup” National Invitational
Contest - Warm Up
AC代码:
#include <map> #include <set> #include <cmath> #include <deque> #include <queue> #include <stack> #include <cstdio> #include <cctype> #include <string> #include <vector> #include <cstdlib> #include <cstring> #include <iostream> #include <algorithm> #define LL long long #define INF 0x7fffffff using namespace std; const int maxn = 20000; int prime[20000]; void init() { prime[1] = 2; for(int i = 2; i < maxn; i ++) if(prime[i] == 0) { prime[i] = 1; for(int j = i * 2; j < maxn; j += i) { prime[j] = 2; } } prime[2] = 2; } int main() { init(); int cas = 1; int a; while(scanf("%d", &a) != EOF) { if(a == 0) break; if(prime[a] == 1) { printf("%d: yes\n", cas ++); } else if(prime[a] == 2) { printf("%d: no\n", cas ++); } } return 0; }