题目大意 给定两个数L和U,要求你求出在区间[L, U] 内所有素数中,相邻两个素数差值最小的两个素数C1和C2以及相邻两个素数差值最大的两个素数D1和D2,并且L-U<1,000,000 题解 由于1<=L< U<=2,147,483,647,直接筛肯定超时,但是题目说L-U<1,000,000,我们可以先筛选出sqrt(2147483647)(约等于46340)内的素数即可,然后再用这些素数把区间[L,U]内的合数筛选掉,最后就可以枚举答案了~~~ 代码: #includ…

链接: https://vjudge.net/problem/POJ-2689 题意: The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousands of years is the question of primality. A…

                                                Prime Distance 只会埃氏筛法的弱鸡今天读了读挑战程序设计120页,明白了求小区间内素数的方法. 突然发现挑战真的是本很好的书,很具有引导性,不过很多地方没有详细证明介绍,适用进阶选手. 题意:给你两个数,求[a,b]内相邻最近的素数对与相邻最远的素数对.但是,a,b的很大,同时b-a<=1e6. 思路:判断一个数b是否为素数只需判断i*i<=b即可,也就是说小于等于b的合数的最大素因子…

Prime Distance Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 13961   Accepted: 3725 Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number th…

Description The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousands of years is the question of primality. A prime number is a number that is…

题目链接:poj 2689 Prime Distance 题意: 给你一个很大的区间(区间差不超过100w),让你找出这个区间的相邻最大和最小的两对素数 题解: 正向去找这个区间的素数会超时,我们考虑逆向思维: 我们先用线性筛 筛出前50000的素数,在int范围内的区间的合数的因子都在我们之前筛出来了, 然后我们就把这个区间的合数标记出来,剩下的就是素数了. 标记合数也是用全部的素数去筛一下,这样就能快速的标记这个区间的合数,然后在暴力枚举一下这个区间,更新一下答案. #include<cst…

题目链接:传送门 题目: Prime Distance Time Limit: 1000MS Memory Limit: 65536K Total Submissions: Accepted: Description The branch of mathematics called number theory and itself). The first prime numbers are ,,, but they quickly become less frequent. One of the…

题目链接: http://poj.org/problem?id=2689 题意: 给出一个区间 [l, r] 求其中相邻的距离最近和最远的素数对 . 其中 1 <= l <  r <= 2,147,483,647, r - l <= 1e6 . 思路: 素数区间筛 要找到 [l, r] 中相邻最近和最远的素数对肯定是需要找出 [l, r] 内所有素数 . 但是无论是直接线性打表还是暴力都处理不了这么大的数据 . 可以先给 sqrt(r) 内的素数打个表, 再用 sqrt(r) 内的…

Prime Distance Time Limit: 2 Seconds      Memory Limit: 65536 KB The branch of mathematics called number theory is about properties of numbers. One of the areas that has captured the interest of number theoreticians for thousands of years is the ques…

题目戳这里 [题目大意] 给定一个区间[L,R],求区间内的质数相邻两个距离最大和最小的. [思路分析] 其实很简单呀,很明显可以看出来是数论题,有关于质数的知识. 要注意一下的就是L和R的数据范围都很大,所以直接跑出1-R的所有质数是不可能的,于是我们就要想办法cut掉一些时间了 然后发现跑出1-的所有质数是不会超时的,接下来就好办了,直接用这些质数去标记出[L,R]区间内的合数,这样就可以在规定时间内得到[L,R]区间内的质数了,把相邻两质数相减再比较一下就可以得出答案啦QWQ [代码实现]…