题:https://codeforces.com/contest/570/problem/D 题意:给定一个以11为根的n个节点的树,每个点上有一个字母(a~z),每个点的深度定义为该节点到11号节点路径上的点数.每次询问a,ba,b查询以aa为根的子树内深度为bb的节点上的字母重新排列之后是否能构成回文串.分析:很明显是个树上启发式合并.显然,只要深度为bb结点的所有颜色中,至多有一种的数量为奇数就可以构成回文串了. #include<bits/stdc++.h> using namespa…

Codeforces Round #588 (Div. 2)-E. Kamil and Making a Stream-求树上同一直径上两两节点之间gcd的和 [Problem Description] 给你一棵树,树上每个节点都有一个权值.定义\(1\sim v\)的最短路径所经过的所有节点\(u\)称为\(v\)节点的祖先.定义函数\(f(u,v)=gcd(u,t1,t2,\dots,v)\),其中\(u,t1,t2,\dots\)都是\(v\)的祖先.求\(\sum f(u,v)\). […

C. Replacement Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/570/problem/C Description Daniel has a string s, consisting of lowercase English letters and period signs (characters '.'). Let's define the operation of replac…

C. ReplacementTime Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/570/problem/C Description Daniel has a string s, consisting of lowercase English letters and period signs (characters '.'). Let's define the operation of replace…

A. Elections time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output The country of Byalechinsk is running elections involving n candidates. The country consists of m cities. We know how many peopl…

A - Elections 题意: 每一场城市选举的结果,第一关键字是票数(降序),第二关键字是序号(升序),第一位获得胜利. 最后的选举结果,第一关键字是获胜城市数(降序),第二关键字是序号(升序),第一位获得胜利. 求最后选举获胜者. 思路: 直接模拟就可以. 代码: /* * @author FreeWifi_novicer * language : C++/C */ #include<cstdio> #include<iostream> #include<cstrin…

题意:给定一个字符串,里面有各种小写字母和' . ' ,无论是什么字母,都是一样的,假设遇到' . . ' ,就要合并成一个' .',有m个询问,每次都在字符串某个位置上将原来的字符改成题目给的字符,问每次须要多少次合并次数.才使字符串没有' .. ' 思路:最原始的想法,就是对于每一次询问,都遍历整个字符串.这样时间复杂度o(n*m),就高达10^10方,非常明显会tle. 换下思路,事实上每次询问所改变的字符都会保留到下一次.也就是下一次的次数就会受到上一次的影响,那么我仅仅要就算出第一次的…

E. Pig and Palindromes   Peppa the Pig was walking and walked into the forest. What a strange coincidence! The forest has the shape of a rectangle, consisting of n rows and m columns. We enumerate the rows of the rectangle from top to bottom with num…

思路:把n分成[1,n/2],[n/2+1,n],假设m在左区间.a=m+1,假设m在右区间,a=m-1.可是我居然忘了处理1,1这个特殊数据.被人hack了. 总结:下次一定要注意了,提交前一定要看下边界数据,不要急着交. 题目链接:http://codeforces.com/problemset/problem/570/B <pre name="code" class="cpp">#include<bits/stdc++.h> using…

D. Tree Requests time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Roman planted a tree consisting of n vertices. Each vertex contains a lowercase English letter. Vertex 1 is the root of the…