You are given an array a consisting of n integers, and additionally an integer m. You have to choose some sequence of indices b1, b2, ..., bk (1 ≤ b1 < b2 < ... < bk ≤ n) in such a way that the value of is maximized. Chosen sequence can be empty.…
题目链接:E. Maximum Subsequence 用了一个Meet-in-the-middle的技巧,还是第一次用到这个技巧,其实这个技巧和二分很像,主要是在dfs中,如果数量减小一半可以节约很多的时间. Meet in the middle(有时候也叫作split and merge)是一种用以获取足够高效解决方案的灵巧的思想.和分治思想非常类似,它将问题分割成两个部分,然后试着合并这两个子问题的结果.好处在于通过使用一点额外的空间,你可以解决两倍规模的原来可以解决的问题. #in…
http://codeforces.com/contest/888 A Local Extrema[水] [题意]:计算极值点个数 [分析]:除了第一个最后一个外,遇到极值点ans++,包括极大和极小 [代码]: #include<bits/stdc++.h> using namespace std; int main() { +]; int maxn,minn; maxn=minn=; cin>>n; ;i<=n;i++) { cin>>a[i]; } ;i&l…
题目链接 题意:给你两个数n,m,和一个大小为n的数组. 让你在数组找一些数使得这些数的和模m最大. 解法:考虑 dfs但是,数据范围不允许纯暴力,那考虑一下折半搜索,一个从头开始往中间搜,一个从后往中间搜.在中间相遇的时间二分更新最大值即可. #include<bits/stdc++.h> #define LL long long #define fi first #define se second #define mp make_pair #define pb push_back usin…
1) Link to the problem: http://codeforces.com/contest/888/problem/C 2) Description: You are given a string s consisting of lowercase Latin letters. Character c is called k-dominant if each substring of s with length at least k contains this character…
A permutation p of size n is an array such that every integer from 1 to n occurs exactly once in this array. Let's call a permutation an almost identity permutation iff there exist at least n - k indices i (1 ≤ i ≤ n) such that pi = i. Your task is t…
After several latest reforms many tourists are planning to visit Berland, and Berland people understood that it's an opportunity to earn money and changed their jobs to attract tourists. Petya, for example, left the IT corporation he had been working…
