题意:给定 n 个数,然后让从中选取一些数使得它们的总乘积最大.如果有多个,要求这些数尽量少,如果还有多个,随便输出一组即可. 析:一个贪心题,根据乘法的性质,很容易知道,如果一个数大于1,那么肯定要选的,然后如果有两个负数乘积大于1,也要选上,其他的尽量不要选. 最后如果没有这样数,那么就只要计算最小的两个数乘积与最大的比较即可,主要是因为是最小的两个可能是负数,如果不是也不影响结果. 这个题在比赛时,竟然没有AC,...主要原因是我没有控制精度,卡了好久,如果控制一下精度就AC了,可以把所有…

传送门 E. Epic Fail of a Genie time limit per test 0.5 seconds memory limit per test 64 megabytes input standard input output standard output Aladdin had found a new shiny lamp and has started polishing it with his hands. Suddenly a mysterious genie app…

题意:给出一堆元素,求一个子集,使子集的乘积最大,如有多个,应该使子集元素个数尽量小. 题解:贪心,如果有大于1的正数,那么是一定要选的,注意负数也可能凑出大于1的正数,那么将绝对值大于1的负数两两配对, 如果还剩下一个绝对值大于1的负数,那么在判断一下,那个负数和比它大的最小负数的乘积是否大于1,如果是那么就选这两个. 把所有可能凑成大于1的数选完以后,剩下的数一定比1小,那么就不选. 如果无法凑出大于1的数,那么再分类讨论一下. 挺容易写错... #include<bits/stdc++.h…

E. Epic Fail of a GenieTime Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100685/problem/E Description Aladdin had found a new shiny lamp and has started polishing it with his hands. Suddenly a mysterious genie appeared from withi…

题目链接 题意:n个数分别为a[i],问是否存在一组对应的b[i],b[i]=1 || b[i]=-1,使得ai*bi的n项和为0. 题解: 先证明一个结论吧,对于1≤ai≤i+1,前面ai个数一定可以凑出1~sum[i]中的任意一个数. 对于i=1显然成立,假设对于i=k结论成立,那么对于i=k+1来说,只要证明sum[k]+i,1≤i≤ak+1可以凑出来就行了. 因为sum[k]+i≥k+1,且1≤ak+1≤k+1,所以可以先选一个ak+1,剩下的0≤sum[k]+i-ak+1≤sum[k]…

作为程序员,我们经常会被客户问的一个问题一定是不是说很容易么,为什么花了这么长时间.不得不说,程序员可能是最糟糕的计划者,按时按点按计划完成的软件项目永远是下一个项目.一个项目的延期,有很多这样那样的原因,其中不得不说的一个原因就是很多代码想起来很容易,但是真的写起来,细节里全是魔鬼.在这个Epic Fail的系列中,我会记录一些在我平常写代码的过程中遇到的那些本来很简单却花了很长时间的有趣问题.这个系列会不定时更新,不断记录我写代码中的糗事,希望我永远不用更新:).   作为开篇,记录一个花了…

一句话题意:x0=1,xi+1=(Axi+xi%B)%C,如果x序列中存在最早的两个相同的元素,输出第二次出现的位置,若在2e7内无解则输出-1. 题解:都不到100天就AFO了才来学这floyd判圈算法. 介绍一下floyd判圈算法:该算法适用于在线性时间复杂度内判断有限自动机.迭代函数.链表中是否有环,求环的起点(即链长)和环长. 可以先这么做:首先从起点S出发,给定两个指针,一个快指针一个慢指针,然后每次快指针走1步,慢指针走2步,直到相遇为止.如果已经到达终点/达到规定步数时仍然没有相遇…

题目传送门 传送门 题目大意 $m$只鼹鼠有$n$个巢穴,$n - 1$条长度为$1$的通道将它们连通且第$i(i > 1)$个巢穴与第$\left\lfloor \frac{i}{2}\right\rfloor$个巢穴连通.第$i$个巢穴在最终时允许$c_i$只醒来的鼹鼠最终停留在这.已知第$i$只鼹鼠在第$p_i$个巢穴睡觉.要求求出对于每个满足$1 \leqslant k \leqslant n$的$k$,如果前$k$只鼹鼠醒来,最小的移动距离的总和. 考虑费用流的建图和暴力做法,把原图的…

题目传送门 传送门 题目大意 给定一个长度为$n$的序列,要求划分成最少的段数,然后将这些段排序使得新序列单调不减. 考虑将相邻的相等的数缩成一个数. 假设没有分成了$n$段,考虑最少能够减少多少划分. 我们将这个序列排序,对于权值相同的一段数可以任意交换它们,每两个相邻数在原序列的位置中如果是$i, i + 1$,那么划分的段数就可以减少1. 每次转移我们考虑添加值相同的一段. 每次转移能不能将减少的段数加一取决于当前考虑的数在前一段内有没有出现以及有没有作为最左端点. 因此我们记录一个决策与…

Codeforces Gym 100725K 题意:给定一个初始全0的序列,然后给\(n\)个查询,每一次调用\(Insert(L_i,i)\),其中\(Insert(L,K)\)表示在第L位插入K,如果第L位已经有值了就会先调用\(Insert(L+1,A_L)\)(其中\(A_L\)表示第L位上的值),再将\(A_L\)赋为K.问经过查询后序列的模样. 思路:首先将题意抽象成每次找到从第L位开始第一个0,并将其"拖"回第L位,然后将其更改为K.这个操作很明显可以用FHQ Treap…

 2017 JUST Programming Contest 2.0 题目链接:Codeforces gym 101343 J.Husam and the Broken Present 2 J. Husam and the Broken Present 2 time limit per test:1.0 s memory limit per test:256 MB input:standard input output:standard output After you helped Husam…

codeforces gym 100553I solution 令a[i]表示位置i的船的编号 研究可以发现,应是从中间开始,往两边跳.... 于是就是一个点往两边的最长下降子序列之和减一 魔改树状数组求min #include<cstdio> #include<iostream> #include<cstdlib> #include<cstring> #include<algorithm> #include<cmath> #defi…

CodeForces Gym题目页面传送门 有\(1\)个\(n1\times m1\)的字符矩阵\(a\)和\(1\)个\(n2\times m2\)的字符矩阵\(b\),求\(a,b\)的最大公共子矩阵.输出这个最大公共子矩阵的行数.列数和左上角分别在\(a,b\)中的坐标.若无解,输出\(\texttt{0 0}\).若有多解,输出任意一组. \(n1,m1,n2,m2\in[1,40]\). 如果你还不知道Gym是什么,please点击这个 (以下假设\(n1,m1,n2,m2\)同阶,…

Codeforces GYM 100876 J - Buying roads 题解 才不是因为有了图床来测试一下呢,哼( 题意 给你\(N\)个点,\(M\)条带权边的无向图,选出\(K\)条边,使得得到的子图联通并且总代价最小,输出最小总代价和一种方案. 虽然题目里描述的很冗长,但其实这个图有一些性质:它最初是一条链/一个环,然后再有一些结点直接连到这些在链上/环上的结点.. 下图就是一个(就是样例): 做法 首先我们可以简单的查看点的度数来找到链/环上的点,和连接它们的边. 然后我们可以通过…

J. Deck Shuffling Time Limit: 2   Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100187/problem/J Description The world famous scientist Innokentiy continues his innovative experiments with decks of cards. Now he has a deck of n cards and k…

K. Perpetuum Mobile Time Limit: 2 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100187/problem/K Description The world famous scientist Innokentiy almost finished the creation of perpetuum mobile. Its main part is the energy generator which…

Problem J. Triatrip Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100342/attachments Description The travel agency “Four Russians” is offering the new service for their clients. Unlike other agencies that only suggest one-way…

Problem C. Painting CottagesTime Limit: 2 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100342/attachments Description The new cottage settlement is organized near the capital of Flatland. The construction company that is building the settl…

Problem A. Poetry Challenge Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100500/attachments Description Let’s check another challenge of the IBM ICPC Chill Zone, a poetry challenge. One says a poetry string that starts with a…

A. Nano alarm-clocks Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100637/problem/A Description An old watchmaker has n stopped nano alarm-clocks numbered with integers from 1 to n. Nano alarm-clocks count time in hours, and…

G. FacePalm Accounting Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/gym/100513/problem/G Description An owner of a small company FacePalm has recently learned that the city authorities plan to offer to small businesses to partic…

http://codeforces.com/gym/101142/attachments 题意:每个人在TC和CF上分别有两个排名,如果有一个人在任意一个网站上大于另一个人的排名,那么这个人可以打败另外一个人.还有就是如果 B 能打败 A, C 能打败 B,但是 C 直接从排名上看 C 并不能打败 A,但是因为 B -> A 并且 C -> B,所以 C -> B -> A, 即 C 也能(通过打败 B 来)打败 A. 如这个样例: A :5, 5 , B :1, 6,  C:2,…

Flipping Parentheses 题目连接: http://codeforces.com/gym/100803/attachments Description A string consisting only of parentheses '(' and ')' is called balanced if it is one of the following. • A string "()" is balanced. • Concatenation of two balance…

Space Golf 题目连接: http://codeforces.com/gym/100803/attachments Description You surely have never heard of this new planet surface exploration scheme, as it is being carried out in a project with utmost secrecy. The scheme is expected to cut costs of c…

There is No Alternative 题目连接: http://codeforces.com/gym/100803/attachments Description ICPC (Isles of Coral Park City) consist of several beautiful islands. The citizens requested construction of bridges between islands to resolve inconveniences of u…

Shopping 题目连接: http://codeforces.com/gym/100803/attachments Description Your friend will enjoy shopping. She will walk through a mall along a straight street, where N individual shops (numbered from 1 to N) are aligned at regular intervals. Each shop…

Joy of Flight 题目连接: http://codeforces.com/gym/100531/attachments Description Jacob likes to play with his radio-controlled aircraft. The weather today is pretty windy and Jacob has to plan flight carefully. He has a weather forecast - the speed and d…

Problem I. Instruction 题目连接: http://codeforces.com/gym/100531/attachments Description Ingrid is a head of a big railway station and, among other duties, is responsible for routing trains to the right platforms. The station has one entrance, and there…

Problem G. Grave 题目连接: http://codeforces.com/gym/100531/attachments Description Gerard develops a Halloween computer game. The game is played on a rectangular graveyard with a rectangular chapel in it. During the game, the player places new rectangul…

Problem D. Digits 题目连接: http://codeforces.com/gym/100531/attachments Description Little Petya likes integers. Recently he has learned about different properties of sums of number's digits. For example, if the sum of number's digits is divisible by 9,…