Coldfresh的博客

Professor Zhang has kinds of characters and the quantity of the ii-th character is aiai. Professor Zhang wants to use all the characters build several palindromic strings. He also wants to maximize the

1.设f(n)f(n)f(n)为n的因子的和，求： ∑i=1nf(i)∑i=1nf(i)\sum_{i=1}^nf(i) 其中n<1012n<1012nans=∑in∑jn[j|i]∗j=∑jnj∑in[j|i]=∑j=1n⌊nj⌋ans=∑in∑jn[j|i]∗j=∑jnj∑in[j|i]=∑j=1n⌊nj⌋ans=\sum_i^n\sum_j^n[j|i]*j\\=\sum_j...

Given a rooted tree with n vertices, some of the vertices are important. An auxiliary set is a set containing vertices satisfying at least one of the two conditions： ∙It is an important vertex ∙...

给出正整数n和k，计算j(n, k)=k mod 1 + k mod 2 + k mod 3 + … + k mod n的值 其中k mod i表示k除以i的余数。 例如j(5, 3)=3 mod 1 + 3 mod 2 + 3 mod 3 + 3 mod 4 + 3 mod 5=0+1+0+3+3=7 Input 输入仅一行，包含两个整数n, k。 1<=n ,k<=10^...

A group of n cities is connected by a network of roads. There is an undirected road between every pair of cities, so there are roads in total. It takes exactly y seconds to traverse any single road....

You are given n segments on the coordinate axis Ox and the number k. The point is satisfied if it belongs to at least k segments. Find the smallest (by the number of segments) set of segments on the c...

Leha somehow found an array consisting of n integers. Looking at it, he came up with a task. Two players play the game on the array. Players move one by one. The first player can choose for his move a

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 indice

You are given a string s consisting of lowercase Latin letters. Character c is called k-dominant iff each substring of s with length at least k contains this character c.You have to find minimum k such

Petya learned a new programming language CALPAS. A program in this language always takes one non-negative integer and returns one non-negative integer as well.In the language, there are only three comm

Teacher BoBo is a geography teacher in the school.One day in his class,he marked NN points in the map,the ii-th point is at (Xi,Yi)(Xi,Yi).He wonders,whether there is a tetrad (A,B,C,D)(A<B,C<D,A≠CorB≠

An abandoned country has n(n≤100000)n(n≤100000) villages which are numbered from 1 to nn. Since abandoned for a long time, the roads need to be re-built. There are m(m≤1000000)m(m≤1000000) roads to be

TIANKENG manages a restaurant after graduating from ZCMU, and tens of thousands of customers come to have meal because of its delicious dishes. Today n groups of customers come to enjoy their meal, and

FJ’s N (1 ≤ N ≤ 10,000) cows conveniently indexed 1…N are standing in a line. Each cow has a positive integer height (which is a bit of secret). You are told only the height H (1 ≤ H ≤ 1,000,000) of t...