Divisors Time Limit: 1000MS   Memory Limit: 65536K Total Submissions: 9940   Accepted: 2924 Description Your task in this problem is to determine the number of divisors of Cnk. Just for fun -- or do you need any special reason for such a useful compu…

题目链接:http://poj.org/problem?id=2992 题目要求:Your task in this problem is to determine the number of divisors of Cnk. Just for fun -- or do you need any special reason for such a useful computation? 题目解析:这题也是TLE了无数遍,首先说一下求因子数目的函数是积性函数,积性函数即f(n)=f(a)*f(b)…

[题目概括] 计算\(C_n^k\)的因子个数. [思路要点] 首先考虑将组合数展开,展开后就是\(\frac {n!}{k!\times (n-k)!}\). 这样就是计算出这些质因子的个数,然后将插值相乘就是答案了. 但是数据较大,所以我们考虑一开始先将所有答案预处理来. 如果是暴力求解,那么就会超时. 我们考虑用归纳法来计算,如果计算出\(C_{n}^{k}\),那么如何计算出\(C_n^{k+1}\). 那么将式子展开,就相差了\(k+1\)和\(n-k+1\),就\(O(n)\)计算一…

E. Number With The Given Amount Of Divisors time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Given the number n, find the smallest positive integer which has exactly n divisors. It is guara…

Description A number whose only prime factors are 2,3,5 or 7 is called a humble number. The sequence 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 12, 14, 15, 16, 18, 20, 21, 24, 25, 27, ... shows the first 20 humble numbers. Now given a humble number, please write…

计算小于n的数中,约数个数最多的数,若有多个最输出最小的一个数. http://hihocoder.com/problemset/problem/1187 对于100有 60 = 2 * 2 * 3 * 5,共 (2 + 1) * (1 + 1) * (1 + 1) = 12个约数. 对于 n <= 10 ^ 16,int最大值为10位,所以这里要用long long.很显然:约数要尽量小,然后小的约数的指数一定大于大的约数的指数. 所以对于 10^16,有质因子:2,3,5,7,11,13,1…

Xenia and Divisors time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Xenia the mathematician has a sequence consisting of n (n is divisible by 3) positive integers, each of them is at most 7…

传送门 时间限制:10000ms 单点时限:1000ms 内存限制:256MB 描述 Given an integer n, for all integers not larger than n, find the integer with the most divisors. If there is more than one integer with the same number of divisors, print the minimum one. 输入 One line with an…

The number of divisors(约数) about Humble Numbers Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 2044    Accepted Submission(s): 1006 Problem DescriptionA number whose only prime factors are 2,3,…

Problem Description mmm is learning division, she's so proud of herself that she can figure out the sum of all the divisors of numbers no larger than 100 within one day!But her teacher said "What if I ask you to give not only the sum but the square-s…