https://www.hackerrank.com/contests/hourrank-13/challenges/arthur-and-coprimes 我们可以枚举每一个p在[2, sqrt(n)]里,然后就是在[p + 1, n / p]中找有多少个数和p互质了. 标准容斥,先算出[1, n / p]中有多少个和p互质,这个是不能用欧拉定理做的,需要把p质因数分解,然后dfs 求解元素X在区间[1, up]中,有多少个数和X互质.(容斥) 思路:把X质因数分解,多了的不要.12 = 2…

Coprime Time Limit: 4000/2000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 849    Accepted Submission(s): 232 Problem Description Please write a program to calculate the k-th positive integer that is coprime with…

题目求[A,B]区间内与N互质数的个数. 可以通过求出区间内与N互质数的个数的前缀和,即[1,X],来得出[A,B]. 那么现在问题是求出[1,X]区间内与N互质数的个数,考虑这个问题的逆问题:[1,X]区间内与N不互质数的个数. 于是就可以先处理出N的所有质因数{p0,p1,p2,...,pn}. 而[1,X]能被pi整除的数有$\lfloor \frac X{p_i} \rfloor$个,再利用容斥原理除掉质因数公倍数重复计数的部分就能求出不互质个数. 最后X减去不互质个数就是互质个数了.…

Description There are n people standing in a line. Each of them has a unique id number. Now the Ragnarok is coming. We should choose 3 people to defend the evil. As a group, the 3 people should be able to communicate. They are able to communicate if…

Co-prime Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 626    Accepted Submission(s): 234  Problem Description Given a number N, you are asked to count the number of integers between A and B…

Co-prime Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 6425    Accepted Submission(s): 2569 Problem Description Given a number N, you are asked to count the number of integers between A and B…

Co-prime 第一发容斥,感觉挺有意思的 →_→ [题目链接]Co-prime [题目类型]容斥 &题意: 求(a,b)区间内,与n互质的数的个数. \(a,b\leq 10^{15}\) &题解: 分析:我们可以先转化下:用(1,b)区间与n互质的数的个数减去(1,a-1)区间与n互质的数的个数,那么现在就转化成求(1,m)区间于n互质的数的个数,如果要求的是(1,n)区间与n互质的数的个数的话,我们直接求出n的欧拉函数值即可,可是这里是行不通的!我们不妨换一种思路:就是求出(1,m…

题目链接: http://acm.hdu.edu.cn/showproblem.php?pid=4135 Co-prime Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others) Total Submission(s): 1176    Accepted Submission(s): 427 Problem Description Given a number N, you are a…

Given a number N, you are asked to count the number of integers between A and B inclusive which are relatively prime to N.Two integers are said to be co-prime or relatively prime if they have no common positive divisors other than 1 or, equivalently,…

题目链接:Coprime pid=5072"> 题面: Coprime Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 262144/262144 K (Java/Others) Total Submission(s): 1181    Accepted Submission(s): 471 Problem Description There are n people standing in a line. Each of t…