During Upsolving, I have seen that some problems can be solved using the prefix sum method way more easily and efficiently. Which topic is new for me. So, I tried practicing it from cses problemset but it has o
Part 1: Fast prefix sum computation Part 2: Dirichlet series and prime counting ecnerwala previously mentioned that it is possible, but did not go into much detail. There is also a blog by Nisiyama_Suzune, which covers prefix sums of Dirichlet inverses in O(n2/3)O(n2/3). Dirichlet ...
codeforces 257D sum 【思维】 题目分析 考虑 0≤a[i+1]−a[i]≤a[i]0 \le a[i+1]- a[i] \le a[i]0≤a[i+1]−a[i]≤a[i] 所以本题倒过来考虑 我们发现,考虑每一个 i, 如果 a[i+1] 的范围在 (a[i],a[i]*2)的范围内的话,那么 我令 x= a[i+1]-a[i] x的范围...
ProblemCodeforces Round #556 (Div. 2)- D. Three Religions Time Limit: 1000 mSec Problem Description Input Output Sample Input 5 1 2 1 2 1 Sample Output 1 1 1 2 2 题解:这个题有做慢了,这种题做慢了和没做出来区别不大。。。 读题的时候脑子里还意识到素数除了2都是奇数,读完之后就脑子里...
prefix sum, probably an empty one which is equal to000(in another words, if every nonempty prefix sum is less to zero, then it is considered equal to zero). Formally, denote asf(a)f(a)f(a)the maximal prefix sum of an arraya1,…,la_{1, \ldots ,l}a1,…,lof lengthl≥0l...
CF1149 A. Prefix Sum Primes 题目传送门:https://codeforces.com/problemset/problem/1149/A 题目大意: 给定一串长度为nn的序列AA,序列AA仅由1,21,2组成,记Si=i∑j=1AjSi=∑j=1iAj,问给序列AA任意排序后,SS中素数最多的情况? 由于素数除2之外都是偶数,故我们只需要构造形如2,1,2,...,2,1,.....
【CF1303G】Sum of Prefix Sums 题目 题目链接:https://codeforces.com/contest/1303/problem/G 有一颗 \(n\) 个节点的树,树每个节点有一个权值 \(a_i (1 \leq a_i \leq 10^6)\)。 定义树上 \(u \rightarrow v\) 的链的权值如下:将 \(u\) 到 \(v\) 的路径上点的权值依次排列在数组中...
CF1149A -PrefixSumPrimes(贪心) 传送门:Problem - 1149A - Codeforces 考虑到除了2以外所有的质数都由奇数组成,因此贪心思路为构造一个数列,使得数列中前缀和为奇数的情况尽量多。 因此可以先输出2和1,再将所有的2输出,最后再输出所有的1,此时得到的前缀和为质数的数量最多。 #include<iostrea ... ...
You can make hacks only if all versions of the problem are solved. There are two binary strings aa and bb of length nn (a binary string is a string consisting of symbols 00 and 11). In an operation, you select a prefix of aa, and simultaneously invert the bits in the prefix (00 ...
Codeforces Round #658 (Div. 1)A1. Prefix Flip (Easy Version)【思维】,代码先锋网,一个为软件开发程序员提供代码片段和技术文章聚合的网站。