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…

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…

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…

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…

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…

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 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…

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…