JXCPC 試題冊

Input file: standard input

Output file: standard output

Time limit: 1s

Memory limit: 256 megabytes

Problem A. Cotree

Avin has two trees which are not connected. He asks you to add an edge between them to make them connected while minimizing the function \(\sum_{i=1}^{n} \sum_{j=i+1}^{n} dis(i,j)\)

,where dis(i,j) represents the number of edges of the path from i to j . He is happy with only the function value.

Input

The first line contains a number n(\(2 \leq n \leq 100,000\)). In each of the following n-2 lines , there are two numbers u and v , meaning that there is an edge between u and v .The input is guaranteed to contain exactly two trees.

Output

Just print the minimum function value

中文簡述題意

給出兩棵樹T1,T2，連接一條邊使得這兩顆樹合成一棵樹，你所連的邊要使\(\sum_{i=1}^{n} \sum_{j=i+1}^{n} dis(i,j)\)最小，dis(i,j)指鏈接i,j的簡單路徑所含邊的數目

Example

• Input

  3 1 2

• Output

  4

Problem B.Math

Avin sells robots to clients. At second 0,Avin is at the location (0,0) on a number axis with a robot. He wants to go to (L,0) with the robot. He walks a unit distance per second , and he can only stop at integer coordinates. Now he decides to follow these walking rules repeatedly until he arrives (L,0) with the robot :

• 1) If Avin has the robot with himself,the robot may be dropped down with probability p

• 2) If Avin had dropped the robot , he will figure it out with probability q. Specially, if Avin arrives at (L,0) without robot , he will trun around immediately

• 3) If Avin does not see that the robot had been dropped, he walks one step right; otherwise, he walks left until he is at the same location as the robot.

What is the expectation of walking time he needs to arrive (L,0) with the robot.

中文簡述題意

Avin要帶著機器人從0走到L，走路速度為每秒一格并且只會在整數格停下，他走路按照以下規則：

• 如果Avin沒有弄丟機器人，則有p的概率弄丟機器人
• 如果Avin已經弄丟了機器人，則有q的概率發現，特別的，當他到達終點卻沒有機器人時，會立刻發現
• 如果Avin發現他弄丟了機器人，則會一直往左走直到遇見機器人，否則他會向右走一格

Input

One line with three numbers L,p and q, where L(\(1\leq L \leq100,000\)) is an integer,p and q are real numbers with three digits and within(0,1)

Output

Print the expected walking time . Your answer is considered correct if the absolute or relative error doesn't exceed \(10^{-6}\).Formally, let you answer be a , and the jury's answer be b. Your answer is considered correct if \(\frac{|a-b|}{max(1,|b|)} \leq 10^{-6}\)

Problem C.Trap

GuGuGu

Problem D.Wave

Avin is studying series. A series is called "wave" if the following conditions are satiffied:

1) It contains at least two elements

2) All elements at odd positions are the same

3) All elements at even positions are the same

4) Elements at odd positions are NOT the same as the elements at even positions

You are given a series with length n. Avin asks you to find the longest "wave" subseries. A subseries is a subsequence of a series.

Input

The first line contains two numbers n,c(\(1 \leq n \leq 100,000, 1 \leq c \leq 100\)). The second line contains n integers whose range is [1,c] , which represents the series. It is guaranteed that there is always a "wave" subseries.

Output

Print the length of the longest "wave" subseries.

插幾句嘴qwq

本題考試時\(O(nc^2)\)可以通過,實際上\(O(nc^2) \leq O(10^5 \times (10^2)^2) = O(10^9)\),不能通過

所以很迷...我寫的是\(O(nc)\)

Example

• Input

  5 3 1 2 1 3 2

• Output

  4

Problem E.Packing

GuGuGu

Problem F.String

Avin has a string. He would like to uniform-randomly select four characters (selecting the same character is allowed) from it. You are asked to calculate to probability of four characters being "avin" in order.

Input

The first line contains n(\(1 \leq n \leq 100\)), the length of the string. The second line contains the string. To simplify the problem , the characters of the string are from 'a' , 'v' , 'i' , 'n'.

Output

Print the reduced fraction (the greatest common divisor of the numerator and denominator is 1),representing the probability. If the answer is 0 , you should output "0/1"

Example

• Input1

  4 avin

• Output1

  1/256

• Input2

  4 aaaa

• Output2

  0/1

Problem G.Traffic

GuGuGu

Problem H.RNG(RNG 牛逼)

Avin is studying how to synthesize data . Given a integer n, he constructs ans interval using the following method: He first generates a integer r between 1 and n (both inclusize) uniform-randomly, and generates a integer l between 1 and r (both inclusize) uniform-randomly. The interval [l,r] is the constructed. Avin has constructed two intervals using the method above. He asks you what the probalility that two intervals intersect(相交) is. You should print \(q \times q^{-1}(MOD 1,000,000,007)\), while \(\frac{p}{q}\) denoting the probalility.

Input

Just one line contains the number n (\(1 \leq n \leq 1,000,000\))

Output

Print the answer

Example

• Input1

  1

• Output1

  1

• Input2

  2

• Output2

  750000006

Problem I.Budget

Avin's company has many ongoing projects with difference budgets. His company records the budgets using numbers rounded to 3 digits after the decimal place.However, the company is updating the system and all budgets will be rounded up to 2 digits after the decimal place. For example, 1.004 will be rounded down to 1.00 while 1.995 will be rounded up to 2.00. Avin wants to konw the difference of the total budget caused by update.

Input

The first line contains an integer n(\(1 \leq n \leq 1,000\)). The second line contains n decimals, and the i-th decimal \(a_i\)(\(0 \leq n \leq 10^{18}\)) repersents the budget of the i-th project. All decimals are rounded to 3 digits.

Output

Print the difference rounded to 3 digits.

Example

• Input1

  1 1.001

• Output1

  -0.001

• Input2

  1 0.999

• Output2

  0.001

• Input3

  2 1.001 0.999

• Output3

  0.000

Problem J.Worker

Avin meets a rich customer today. He will earn 1 million dollars if he can solve a hard problem. There are n warehouses and m workers. Any worker in the i-th warehouse can handle \(a_i\) orders per day. The customer wonders whether there exists one worker assignment method satiisfying that every warehouse handles the ssame number of orders every day. Note that each worker should be assigned to exactly warehouse and no worker is lazy when working.

Input

The first line contains two integers n(\(1 \leq n \leq 1,000\)) ,m(\(1 \leq m \leq 10^{18}\)). The second lie contains n integers. The i-th integer \(a_i\) (\(1 \leq a_i \leq 10\)) represensts one worker in the i-th warehouse can handle \(a_i\) orders per day.

Output

If there is feasible assignment method, orint "Yes" in the first line. Then , i th second line, print n integers with i-th integer representing the number of workers assigned too the i-th warehouse. Otherwise , print "No" in one line. If there are multiple solutions, any is accepted.

Example

• Input1

  2 6 1 2

• Output1

  Yes 4 2

• Input2

  2 5 1 2

• Output2

  No

Problem K.Class

Avin has two integers a,b(\(1 \leq a,b \leq 1,000\)).

Given x=a+b and y=a-b, can you calculate a*b?

Input

The first line contains two integers x,y.

Output

Print the result of a*b.

Example

• Input1

  4 2

• Output1

  3

轉載于:https://www.cnblogs.com/tyqtyq/p/11161504.html

與50位技術專家面對面20年技術見證，附贈技術全景圖

總結

以上是生活随笔為你收集整理的JXCPC 试题册的全部內容，希望文章能夠幫你解決所遇到的問題。

如果覺得生活随笔網站內容還不錯，歡迎將生活随笔推薦給好友。