Divisor Summation Problem Description Give a natural number n (1 <= n <= 500000), please tell the summation of all its proper divisors. Definition: A proper divisor of a natural number is the divisor that is strictly less than the number. e.g. numbe…

Problem Introduction The greatest common divisor \(GCD(a, b)\) of two non-negative integers \(a\) and \(b\) (which are not both equal to 0) is the greatest integer \(d\) that divides both \(a\) and \(b\). Problem Description Task.Given two integer \(…

One efficient way to compute the GCD of two numbers is to use Euclid's algorithm, which states the following: GCD(A, B) = GCD(B, A % B) GCD(A, 0) = Absolute value of A In other words, if you repeatedly mod A by B and then swap the two values, eventua…

Divisor counting 题目大意:定义f(n)表示整数n的约数个数.给出正整数n,求f(1)+f(2)+...+f(n)的值. 注释:1<=n<=1000,000 想法:我们再次有两种做法:文...武......想讲武的......我们其实这次更博只是为了介绍一种知识点——线性筛法筛积性函数.这里,给出线性筛的万能筛法. 1.初值:显然,初值是必要的. 2.我们类比欧拉筛,用k(n)举例.当n是素数时的情况使我们必须的,这相当于初值一样重要. 3.又因为,我们主要筛积性函数,显然函数…

定义: 最大公约数(英语:greatest common divisor,gcd).是数学词汇,指能够整除多个整数的最大正整数.而多个整数不能都为零.例如8和12的最大公因数为4. 最小公倍数是数论中的一个概念.若有一个数\[X\],可以被另外两个数\[A\].\[B\]整除,且\[X\]大于(或等于)\[A\]和\[B\],则\[X\]X为\[A\]和\[B\]的公倍数.\[A\]和\[B\]的公倍数有无限个,而所有的公倍数中,最小的公倍数就叫做最小公倍数.两个整数公有的倍数称为它们的公倍数,…

Description You are given an integer number nn. The following algorithm is applied to it: if n=0, then end algorithm; find the smallest prime divisor d of n; subtract dd from n and go to step 1. Determine the number of subtrations the algorithm will…

描述 Given two numbers, number a and number b. Find the greatest common divisor of the given two numbers. In mathematics, the greatest common divisor (gcd) of two or more integers, which are not all zero, is the largest positive integer that divides ea…

本题有两个难点: 1 大量的数据输入.没处理好就超时 - 这里使用buffer解决 2 因子分解的算法 a)暴力法超时 b)使用sieve(筛子),只是当中的算法逻辑也挺不easy搞对的. 数值N因子分解逻辑: 1 保存全部能够sqrt(N)范围内的质素 2 找到能够被N除尽的质素d, 然后用d去除N.使用deg变量,保存度.即有多少个d能够被N除尽 3 用d去乘全部已经找到的因子(包含1),假设度deg大于1.那么循环i从1到deg, 用d*i去乘全部找到的因子 找到全部因子相加,减去N,就是…

B. Weakened Common Divisor time limit per test 1.5 seconds memory limit per test 256 megabytes input standard input output standard output During the research on properties of the greatest common divisor (GCD) of a set of numbers, Ildar, a famous mat…

Greatest Greatest Common Divisor Time Limit: 1 Sec  Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5207 Description 在数组a中找出两个数ai,aj(i≠j),使得两者的最大公约数取到最大值. Input 多组测试数据.第一行一个数字T,表示数据组数.对于每组数据,第一行是一个数n,表示数组中元素个数,接下来一行有n个数,a1到an.1≤T≤…