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3792:Twin Prime Conjecture

题目描述
If we define dn as: dn = pn+1-pn, where pi is the i-th prime. It is easy to see that d1 = 1 and dn=even for n>1. Twin Prime Conjecture states that "There are infinite consecutive primes differing by 2".
Now given any positive integer N (< 10^5), you are supposed to count the number of twin primes which are no greater than N.
输入解释
Your program must read test cases from standard input.
The input file consists of several test cases. Each case occupies a line which contains one integer N. The input is finished by a negative N.
输出解释
For each test case, your program must output to standard output. Print in one line the number of twin primes which are no greater than N.
输入样例
1
5
20
-2
输出样例
0
1
4
来自杭电HDUOJ的附加信息
Recommend notonlysuccess

该题目是Virtual Judge题目,来自 杭电HDUOJ

源链接: HDU-3792

最后修改于 2020-10-25T23:07:03+00:00 由爬虫自动更新

共提交 0

通过率 --%
时间上限 内存上限
2000/1000MS(Java/Others) 32768/32768K(Java/Others)