We call a string as a 0689-string if this string only consists of digits '0', '6', '8' and '9'. Given a 0689-string $s$ of length $n$, one must do the following operation exactly once: select a non-empty substring of $s$ and rotate it 180 degrees. Mo…

BaoBao has just found a grid with $n$ rows and $m$ columns in his left pocket, where the cell in the $j$-th column of the $i$-th row (indicated by $(i, j)$) contains an arrow (pointing either upwards, downwards, leftwards or rightwards) and an intege…

Tree Ming and Hong are playing a simple game called nim game. They have nn piles of stones numbered 11 to nn ,the ii-th pile of stones has a_iai​ stones. There are n - 1n−1 bidirectional roads in total. For any two piles, there is a unique path from…

Travel There are nn planets in the MOT galaxy, and each planet has a unique number from 1 \sim n1∼n. Each planet is connected to other planets through some transmission channels. There are mm transmission channels in the galaxy. Each transmission cha…

Swap There is a sequence of numbers of length nn, and each number in the sequence is different. There are two operations: Swap the first half and the last half of the sequence (if nn is odd, the middle number does not change) Swap all the numbers in…

Angel's Journey “Miyane!” This day Hana asks Miyako for help again. Hana plays the part of angel on the stage show of the cultural festival, and she is going to look for her human friend, Hinata. So she must find the shortest path to Hinata’s house.…

Tasks It's too late now, but you still have too much work to do. There are nn tasks on your list. The ii-th task costs you t_iti​seconds. You want to go to bed TT seconds later. During the TT seconds, you can choose some tasks to do in order to finis…

链接:https://nanti.jisuanke.com/t/39277 思路: 一开始看着很像树分治,就用树分治写了下,发现因为异或操作的特殊性,我们是可以优化树分治中的容斥操作的,不合理的情况只有当两点在一条链上才存在,那么直接一遍dfs从根节点向下跑途中维护一下前缀和,把所有情况中不合理情况造成的值修正. 这样的话时间复杂度就可以降得非常低了,感觉还可以优化,但是懒得写了 代码耗时:142ms. 实现代码: #include<bits/stdc++.h> using namespace…

题目来源 The 2018 ACM-ICPC China JiangSu Provincial Programming Contest 35.4% 1000ms 65536K Persona5 Persona5 is a famous video game. In the game, you are going to build relationship with your friends. You have N friends and each friends have his upper b…

Let's consider some math problems. JSZKC has a set A=A={1,2,...,N}. He defines a subset of A as 'Meo set' if there doesn't exist two integers in this subset with difference one. For example, When A={1,2,3},{1},{2},{3},{1,3} are 'Meo set'. For each 'M…