1770. Alex and Prime

单点时限: 2.0 sec

内存限制: 256 MB

When Kid came back, he was very tired. AK’s another member Alex would like to play with him, so gave him a problem about prime. You should help Kid, or he would never get time to rest.

A prime number is a number that is has no proper factors (it is only evenly divisible by 1 and itself). The first prime numbers are 2,3,5,7 but they quickly become less frequent. Adjacent primes are two numbers that are both primes, but there are no other prime numbers between the adjacent primes. For example, 2,3 are the only adjacent primes that are also adjacent numbers.


The problem is like this: You are given 2 numbers: L and U (1<=L< U<=2,147,483,647 && U - L<=10000000 ), and you are to find the two adjacent primes C1 and C2 (L<=C1< C2<=U) that are closest (i.e. C2-C1 is the minimum).


If there are other pairs that are the same distance apart, use the first pair. You are also to find the two adjacent primes D1 and D2 (L<=D1< D2<=U) where D1 and D2 are as distant from each other as possible (again choosing the first pair if there is a tie).


2 17
14 17
2,3 are closest, 7,11 are most distant.
There are no adjacent primes.

17 人解决,35 人已尝试。

25 份提交通过,共有 142 份提交。

6.3 EMB 奖励。

创建: 14 年,3 月前.

修改: 4 年,5 月前.

最后提交: 7 年,2 月前.

来源: 成都赛区选拔赛