P4287-[SHOI2011]双倍回文 题目: 题目描述: 记字符串$w$的倒置为$w^R$。例如$(abcd)^R=dcba$，$(abba)

P4555-[国家集训队]最长双回文串 题目: 题目描述: 顺序和逆序读起来完全一样的串叫做回文串。比如acbca是回文串，而abc不是（abc的

CF17E-Palisection 题目: 题目描述: In an English class Nick had nothing to do at all, and remembered about wonderful strings called palindromes. We should remind you that a string is called a palindrome if it can be read the same way both from left to right and from right to left. Here are examples of such strings: «eye», «p

P1659-[国家集训队]拉拉队排练 题目: 题目描述: 艾利斯顿商学院篮球队要参加一年一度的市篮球比赛了。拉拉队是篮球比赛的一个看点，好的拉拉队

CF383C-Propagating tree 题目: 题目描述: Iahub likes trees very much. Recently he discovered an interesting tree named propagating tree. The tree consists of $ n $ nodes numbered from $ 1 $ to $ n $ , each node $ i $ having an initial value $ a_{i} $ . The root of the tree is node $ 1 $ . This tree has a

CF85D-Sum of Medians 题目: 题目描述: In one well-known algorithm of finding the $ k $ -th order statistics we should divide all elements into groups of five consecutive elements and find the median of each five. A median is called the middle element of a sorted array (it’s the third largest element for a group of five). To increase the algorithm’s performance speed on