题意:给定n,求三个不同的数满足,2/n = 1/x + 1/y + 1/z. 析:首先1是没有解的,然后其他解都可以这样来表示 1/n, 1/(n+1), 1/(n*(n+1)),这三个解. 代码如下: #pragma comment(linker, "/STACK:1024000000,1024000000") #include <cstdio> #include <string> #include <cstdlib> #include <…

Codeforces Round #384 (Div. 2) 题目链接:Vladik and fractions Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer \(n\) he can represent fraction \(\frac{2}{n}\) as a sum of three distinct posi…

C. Vladik and fractions 题目链接 http://codeforces.com/contest/743/problem/C 题面 Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer n he can represent fraction as a sum of three distinct posit…

codeforces 811E Vladik and Entertaining Flags 题面 \(n*m(1<=n<=10, 1<=m<=1e5)\)的棋盘,每个格子有一个值. 定义联通块:联通块中所有格子的值相等,并且格子四联通. \(1e5\)次询问,每次询问子矩形\((1, l, n, r)\)中联通块的数量. 题解 线段树区间合并. \(cnt[rt]\):区间中联通块个数 \(pre[rt][]\):在区间中用并查集维护端点的连通性.在给合并之后的集合重新编号时,要注…

[CodeForces - 1225D]Power Products [数论] [分解质因数] 标签:题解 codeforces题解 数论 题目描述 Time limit 2000 ms Memory limit 524288 kB Source Technocup 2020 - Elimination Round 2 Tags hashing math number theory *1900 Site https://codeforces.com/problemset/problem/1225…

Bash and a Tough Math Puzzle CodeForces 914D 线段树+gcd数论 题意 给你一段数,然后小明去猜某一区间内的gcd,这里不一定是准确值,如果在这个区间内改变一个数的值(注意不是真的改变),使得这个区间的gcd是小明所猜的数也算小明猜对.另一种操作就是真的修改某一点的值. 解题思路 这里我们使用线段树,维护区间内的gcd,判断的时候需要判断这个区间的左右子区间的gcd是不是小明猜的数的倍数或者就是小明猜的数,如果是,那么小明猜对了.否则就需要进入这个区间…

time limit per test1 second memory limit per test256 megabytes inputstandard input outputstandard output Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer n he can represent fraction as…

传送门 Description Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer n he can represent fraction   as a sum of three distinct positive fractions in form . Help Vladik with that, i.e for a g…

题目链接:Codeforces 396B On Sum of Fractions 题解来自:http://blog.csdn.net/keshuai19940722/article/details/20076297 题目大意:给出一个n,ans = ∑(2≤i≤n)1/(v(i)*u(i)), v(i)为不大于i的最大素数,u(i)为大于i的最小素数, 求ans,输出以分式形式. 解题思路:一開始看到这道题1e9,暴力是不可能了,没什么思路,后来在纸上列了几项,突然想到高中时候求等差数列时候用到…

原题链接:https://vjudge.net/contest/331993#problem/I Vladik and Chloe decided to determine who of them is better at math. Vladik claimed that for any positive integer n he can represent fraction as a sum of three distinct positive fractions in form . Hel…