Lucky7 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=5768 Description When ?? was born, seven crows flew in and stopped beside him. In its childhood, ?? had been unfortunately fall into the sea. While it was dying, seven dolphins arched its body an…

Frogs Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others)Total Submission(s): 1315    Accepted Submission(s): 443 Problem Description There are m stones lying on a circle, and n frogs are jumping over them.The stones a…

给出n个数,给出m个询问,询问 区间[l,r] [u,v],在两个区间内分别取一个数,两个的和为k的对数数量. $k<=2*N$,$n <= 30000$ 发现可以容斥简化一个询问.一个询问的答案为 $[l,v]+(r,u)-[l,u)-(r,v]$,那么我们离线询问,将一个询问分成四个,分块暴力就行了. 然后就是注意细节,不要发生越界,访问错位置之类比较蠢的问题了. /** @Date : 2017-09-24 19:54:55 * @FileName: HDU 5213 分块 容斥.cpp…

求满足$1<=X<=N ,(X,N)>=M$的个数,其中$N, M (2<=N<=1000000000, 1<=M<=N)$. 首先,假定$(x, n)=m$,那么 $(\frac{x}{n},\frac{n}{m})=1$,故$$ans=\sum_{i=m}^{n}\varphi(\frac{n}{i})$$ ん?遅い! $$\sum_{i=m}^{n}\varphi(\frac{n}{i})=\sum\limits_{d|n}{\varphi(\frac{n}…

题目链接:http://acm.hdu.edu.cn/showproblem.php?pid=5768 给你n个同余方程组,然后给你l,r,问你l,r中有多少数%7=0且%ai != bi. 比较明显的中国剩余定理+容斥,容斥的时候每次要加上个(%7=0)这一组. 中间会爆longlong,所以在其中加上个快速乘法(类似快速幂).因为普通的a*b是直接a个b相加,很可能会爆.但是你可以将b拆分为二进制来加a,这样又快又可以防爆. //#pragma comment(linker, "/STACK…

Lucky7 Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 65536/65536 K (Java/Others) Problem Description When ?? was born, seven crows flew in and stopped beside him. In its childhood, ?? had been unfortunately fall into the sea. While it was d…

[题目链接] http://acm.hdu.edu.cn/showproblem.php?pid=5768 [题目大意] 求出一个区间内7的倍数中,对于每个ai取模不等于bi的数的个数. [题解] 首先,对于x mod 7=0,和选取的一些x mod ai=bi,我们可以利用CRT解出最小的x值,那么这样子我们就可以对所有的aibi选取方式做容斥,得到x mod 7=0成立且所有x mod ai=bi不成立的x的个数.也就是答案. [代码] #include <cstdio> #include…

GCD 题目连接: http://acm.hdu.edu.cn/showproblem.php?pid=1695 Description Given 5 integers: a, b, c, d, k, you're to find x in a...b, y in c...d that GCD(x, y) = k. GCD(x, y) means the greatest common divisor of x and y. Since the number of choices may be…

Frogs Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://acm.hdu.edu.cn/showproblem.php?pid=5514 Description There are m stones lying on a circle, and n frogs are jumping over them.The stones are numbered from 0 to m−1 and the frogs are numbered fro…

http://acm.hdu.edu.cn/showproblem.php?pid=5212 题意:忽略.. 题解:把题目转化为求每个gcd的贡献.(http://www.cnblogs.com/z1141000271/p/7419717.html 和这题类似 反向容斥)这里先用容斥写了,mobious的之后再说吧23333. 然后比较想说的是这个调和级数的复杂度 nlog(n) ac代码: #include <iostream> #include <cstdio> #includ…