D. Puzzles Barney lives in country USC (United States of Charzeh). USC has n cities numbered from 1 through n and n - 1 roads between them. Cities and roads of USC form a rooted tree (Barney's not sure why it is rooted). Root of the tree is the city…

D. Puzzles time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Barney lives in country USC (United States of Charzeh). USC has n cities numbered from 1 through n and n - 1 roads between them. C…

期望计算的套路: 1.定义:算出所有测试值的和,除以测试次数. 2.定义:算出所有值出现的概率与其乘积之和. 3.用前一步的期望,加上两者的期望距离,递推出来. 题意: 一个树,dfs遍历子树的顺序是随机的.所对应的子树的dfs序也会不同.输出每个节点的dfs序的期望   思路: 分析一颗子树: 当前已知节点1的期望为1.0 ->anw[1]=1.0 需要通过节点1递推出节点2.4.5的期望值 1的儿子分别是2.4.5,那么dfs序所有可能的排列是6种: 1:1-2-4-5  (2.4.5节点的…

题目链接:http://codeforces.com/problemset/problem/697/D 给你一个有规则的二叉树,大概有1e18个点. 有两种操作:1操作是将u到v上的路径加上w,2操作是求u到v上的路径和. 我们可以看出任意一个点到1节点的边个数不会超过64(差不多就是log2(1e18)),所以可以找最近相同祖节点的方式写. 用一条边的一个唯一的端点作为边的编号(比如1到2,那2就为这条边的编号),由于数很大,所以用map来存. 进行1操作的时候就是暴力加w至u到LCA(u,v…

2018-03-16 http://codeforces.com/problemset/problem/697/C C. Lorenzo Von Matterhorn time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Barney lives in NYC. NYC has infinite number of intersect…

A. Pineapple Incident time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Ted has a pineapple. This pineapple is able to bark like a bulldog! At time t (in seconds) it barks for the first time.…

题目的大意是,给你 m 个数字,让你从中选 n 个,使得选出的数字的极差最小. 好吧,超级大水题.因为要极差最小,所以当然想到要排个序咯,然后去连续的 n 个数字,因为数据不大,所以排完序之后直接暴力就OK了. 附AC代码: 1: #include <stdio.h> 2: #include <math.h> 3: #include <iostream> 4: #include <cstdarg> 5: #include <algorithm>…

B. Barnicle time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Barney is standing in a bar and starring at a pretty girl. He wants to shoot her with his heart arrow but he needs to know the di…

A. Pineapple Incident time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Ted has a pineapple. This pineapple is able to bark like a bulldog! At time t (in seconds) it barks for the first time.…

B. Barnicle time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Barney is standing in a bar and starring at a pretty girl. He wants to shoot her with his heart arrow but he needs to know the di…