Codeforces Round #405 (rated, Div. 2, based on VK Cup 2017 Round 1) 全场题解 菜鸡只会A+B+C,呈上题解: A. Bear and Big Brother 题意:我也没看太清,就是给你两个10以内的数a,b.a每天乘以3,b每天乘以2,求多少天后a大于b. 思路:应该是有公式的,不过看到数据这么小直接暴力乘求解.官方题解貌似就是这样,数据小就是水题. const int N=1e3+10; int main() { int a…

A. Is it rated? time limit per test:2 seconds memory limit per test:256 megabytes input:standard input output:standard output Is it rated? Here it is. The Ultimate Question of Competitive Programming, Codeforces, and Everything. And you are here to a…

A. Is it rated? time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Is it rated? Here it is. The Ultimate Question of Competitive Programming, Codeforces, and Everything. And you are here to a…

A. Vicious Keyboard time limit per test:2 seconds memory limit per test:256 megabytes input:standard input output:standard output Tonio has a keyboard with only two letters, "V" and "K". One day, he has typed out a string s with only t…

和FallDream组队瞎打一通--B两个人写的都挂了233,最后只剩下FallDream写的A和我写的C,最后我yy了个E靠谱做法结果打挂了,结束之后改了改就A了,难受. AC:AC Rank:180 Rating:2133-8->2125 A.Bear and Friendship Condition 题目大意:问一个无向图是否满足若a到b有边且b到c有边则a到c有边.(n<=150,000) 思路:判定每个连通块是不是团,不是则不满足,复杂度O(n). #include<cstdi…

A. Vicious Keyboard 题意:给你一个字符串,里面只会包含VK,这两种字符,然后你可以改变一个字符,你要求VK这个字串出现的次数最多. 题解:数据范围很小,暴力枚举改变哪个字符,然后check就好. #include<bits/stdc++.h> using namespace std; int main(){ string s; cin>>s; int ans = 0; for(int i=0;i<s.size();i++){ if(s[i]=='V'){…

A. Vicious Keyboard time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Tonio has a keyboard with only two letters, "V" and "K". One day, he has typed out a string s with only t…

地址:http://codeforces.com/contest/807/problem/D 题目: D. Dynamic Problem Scoring time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Vasya and Petya take part in a Codeforces round. The round las…

Description Bear Limak prepares problems for a programming competition. Of course, it would be unprofessional to mention the sponsor name in the statement. Limak takes it seriously and he is going to change some words. To make it still possible to re…

771C Bear and Tree Jumps 大意: 给定树,每步能走到距离不超过$k$的任意点,记$f(s,t)$为$s$到$t$的最少步数,求$\sum\limits_{s<t}f(s,t)$ 对于路径$(u,v)$, 假设距离为$d$, 那么贡献为$\lceil\frac{d}{k}\rceil=\frac{d+(-d\text{%}k+k)\text{%}k}{k}$ 也就是说枚举每条边的贡献算出总路径长, 再$O(nk^2)$的$dp$求出多余部分, 最后除以$k$即为答案 #in…

FallDream打的AB都FFT了,只剩一个我打的C,没进前一百,之后看看马拉松复活赛有没机会呗. A. Voltage Keepsake 题目大意:n个东西,每个东西一开始有bi能源,每秒消耗ai能源,每秒可以给一个东西加p能源,秒可以为实数,问至多多少秒内所有东西能源一直为正.(n<=100,000) 思路:二分答案,随便check一下.不特判无解可能会炸精度. #include<cstdio> #include<algorithm> using namespace s…

C. Bear and Different Names 题目连接: http://codeforces.com/contest/791/problem/C Description In the army, it isn't easy to form a group of soldiers that will be effective on the battlefield. The communication is crucial and thus no two soldiers should s…

B. Bear and Friendship Condition 题目连接: http://codeforces.com/contest/791/problem/B Description Bear Limak examines a social network. Its main functionality is that two members can become friends (then they can talk with each other and share funny pic…

A 每次可以换一个或不换,暴力枚举位置即可 B 模拟 C 二分答案.. 边界可以优化r=totb/(tota-p),二分可以直接(r-l>=EPS,EPS不要太小,合适就好),也可以直接限定二分的次数(防止死循环! 一开始EPS=1e-10,结果TLE) 注意精度问题 long double,在统计和的时候注意long long…

A 读题题 B 就是你排名第p,得了x分,而最终至少需要y分,你需要最少的successful hack,使得最终得分s>=y,且由s随机取25个数,使p被选中. (1)暴力枚举hack成功几次,失败几次就好了 (2)另解:枚举尽可能小的s,使|s-x|=0(mod 50),分类讨论 If s ≤ x, we need 0 successful hacks, since we can just make (x - s) / 50 unsuccessful hacks. If s > x and…

A 模拟 B 发现对于每个连通块,只有为完全图才成立,然后就dfs C 构造 想了20分钟才会,一开始想偏了,以为要利用相邻NO YES的关系再枚举,其实不难.. 考虑对于顺序枚举每一个NO/YES,与前一个需要用的的字符串有k-1个交集,只多了一个string 于是只要保证k-1个string不同,只通过当前的string来影响答案, 若YES,开一个新的串: NO,则和第一个串一样,以此让这个相同串在下一次枚举中消失.. //怎么想到? 其实NO可能有多个相同名字,关系就很乱了,我们希望只有…

A. Bear and Big Brother time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Bear Limak wants to become the largest of bears, or at least to become larger than his brother Bob. Right now, Limak…

地址:http://codeforces.com/contest/807/problem/C 题目: C. Success Rate time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are an experienced Codeforces user. Today you found out that during y…

地址:http://codeforces.com/contest/801/problem/D 题目: D. Volatile Kite time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You are given a convex polygon P with n distinct vertices p1, p2, ..., p…

地址:http://codeforces.com/contest/801/problem/C 题目: C. Voltage Keepsake time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output You have n devices that you want to use simultaneously. The i-th devi…

我们要统计的答案是sigma([L/K]),L为路径的长度,中括号表示上取整. [L/K]化简一下就是(L+f(L,K))/K,f(L,K)表示长度为L的路径要想达到K的整数倍,还要加上多少. 于是,我们现在只需要统计sigma((L+f(L,K))),最后除以K即可. 统计sigma(L)时,我们考虑计算每条边出现在了几条路径中,设u为edgei的子节点,那么这条边对答案的贡献就是siz(u)*(n-siz(u)),siz(u)为u的子树大小. 统计sigma(f(L,K))时,我们需要dp出…

如果某个位置i是Y,直接直到i+m-1为止填上新的数字. 如果是N,直接把a[i+m-1]填和a[i]相同即可,这样不影响其他段的答案. 当然如果前面没有过Y的话,都填上0就行了. #include<cstdio> #include<string> #include<iostream> using namespace std; int n,m,a[60],e; string ma[60]; int main(){ // freopen("a.in",…

Description A tree is an undirected connected graph without cycles. The distance between two vertices is the number of edges in a simple path between them. Limak is a little polar bear. He lives in a tree that consists of n vertices, numbered 1 throu…

Description In the army, it isn't easy to form a group of soldiers that will be effective on the battlefield. The communication is crucial and thus no two soldiers should share a name (what would happen if they got an order that Bob is a scouter, if…

Description Bear Limak examines a social network. Its main functionality is that two members can become friends (then they can talk with each other and share funny pictures). There are n members, numbered 1 through n. m pairs of members are friends.…

Description Bear Limak wants to become the largest of bears, or at least to become larger than his brother Bob. Right now, Limak and Bob weigh a and b respectively. It's guaranteed that Limak's weight is smaller than or equal to his brother's weight.…

E. Prairie Partition It can be shown that any positive integer x can be uniquely represented as x = 1 + 2 + 4 + ... + 2k - 1 + r, where k and r are integers, k ≥ 0, 0 < r ≤ 2k. Let's call that representation prairie partition of x. For example, the p…

VK Cup 2012 Round 3 (Unofficial Div. 2 Edition) 代码 VK Cup 2012 Round 3 (Unofficial Div. 2 Edition) A. Problem About Equation 每个杯子体积\[V=\frac{b+\sum{a_i}}{n}\] 判断是否有\(a_i > V\). B. File List 处理出'.'的位置. 第一个'.'和最后一个'.'特判字符长度是否合法. 连续的两点位置差\(d\in[2, 11]\)…

CF上的VK Cup 2017资格赛1,好像很水,因为只有俄文所以语言是最大的障碍--不过之后正式赛貌似就有英文了.(比赛貌似只有开俄文模式才看的到--) 时长1天,不随时间扣分.FallDream dalao跟我组队,我紧抱大腿.共4题,FallDream随手AK,顺便给我面子让我写了道A,我表示非常感激. A.Год поступления в университет 题目大意:一个人参加了n个小组,给出每个小组的对应年份,能参加一个小组当且仅当这个人的入学年份和小组的年份不超过隐藏的一个值…

VK Cup 2015 - Round 1 (unofficial online mirror, Div. 1 only)E. The Art of Dealing with ATM Time Limit: 2 Sec  Memory Limit: 256 MBSubmit: xxx  Solved: 2xx 题目连接 http://codeforces.com/contest/529/problem/E Description ATMs of a well-known bank of a sm…