[CF878E]Numbers on the blackboard 题意:给你一个长度为n个数列,你每次可以进行如下操作: 选取两个相邻的数x,y(x在y左面),然后将这两个数去掉,用x+2y替换它. 重复此操作直到序列中只有一个数为止.你可以任意决定每次合并哪两个数,求最后得到的数的最大值. 为了加大难度,现有q次询问,每次询问给出l,r,问你对[l,r]这段区间进行操作能得到的最大值是什么. n,q<=100000,ai<=10^9 题解:先不考虑l,r的限制,整个操作可以看成:让你最大化…

LINK:Numbers on the blackboard 看完题觉得很难. 想了一会发现有点水 又想了一下发现有点困难. 最终想到了 但是实现的时候 也很难. 先观察题目中的这个形式 使得前后两个数字变成x+2y. 那么一个数字的变成两倍的次数固定 除了左端点至少可以变化一次. 有些数字 可以变换多次 这取决于什么 容易考虑到右端点 先变化一次 如果>0显然 可以和其左边进行合并一下. 然后 可以变换更多次 然后从右到左考虑这个过程就发现是正确的了. 这样 我们得到了一个nm的做法. 容易发…

Codeforces 878 E. Numbers on the blackboard 解题思路 有一种最优策略是每次选择最后面一个大于等于 \(0\) 的元素进行合并,这样做完以后相当于给这个元素乘 \(2\) ,并且不使前面一个元素的值增加了.但是按照这样的策略做不太好维护,考虑做完以后有许多块,除了第一个块以外每一个块都是负的,然后将这些块与第一个块合并.那么用并查集维护一下每个块,每一个元素被乘 \(2\) 的次数就是这个块里面位置比它小的元素个数.定义一个块的和为每个元素乘上其对应系数…

The k-th Largest Group Time Limit: 2000MS   Memory Limit: 131072K Total Submissions: 8807   Accepted: 2875 Description Newman likes playing with cats. He possesses lots of cats in his home. Because the number of cats is really huge, Newman wants to g…

Find them, Catch them Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 42416   Accepted: 13045 Description The police office in Tadu City decides to say ends to the chaos, as launch actions to root up the TWO gangs in the city, Gang Drago…

传送门 Find them, Catch them Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 42463   Accepted: 13065 Description The police office in Tadu City decides to say ends to the chaos, as launch actions to root up the TWO gangs in the city, Gang D…

A Bug's Life Time Limit: 15000/5000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)Total Submission(s): 14121    Accepted Submission(s): 4603 Problem Description Background Professor Hopper is researching the sexual behavior of a rare s…

Find them, Catch them Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 43132   Accepted: 13257 Description The police office in Tadu City decides to say ends to the chaos, as launch actions to root up the TWO gangs in the city, Gang Drago…

True Liars Time Limit: 1000MS   Memory Limit: 10000K Total Submissions: 2713   Accepted: 868 Description After having drifted about in a small boat for a couple of days, Akira Crusoe Maeda was finally cast ashore on a foggy island. Though he was exha…

Navigation Nightmare Time Limit: 2000MS   Memory Limit: 30000K Total Submissions: 5939   Accepted: 2102 Case Time Limit: 1000MS Description Farmer John's pastoral neighborhood has N farms (2 <= N <= 40,000), usually numbered/labeled 1..N. A series o…