Description Twilight Sparkle was playing Ludo with her friends Rainbow Dash, Apple Jack and Flutter Shy. But she kept losing. Having returned to the castle, Twilight Sparkle became interested in the dice that were used in the game. The dice has m fac…

Codeforces VP/补题小记 1149 C. Tree Generator 给你一棵树的括号序列,每次交换两个括号,维护每次交换之后的直径. ​ 考虑括号序列维护树的路径信息和,是将左括号看做 \(-1\) ,右括号看做 \(1\) ,那么一段竖直向上的路径可以表示为括号序列的一个区间和,一段竖直向下的路径可以看做括号序列的一个区间和的相反数.我们要维护的是树的直径,也就是一段连续的和减去紧随其后的一段连续的差.具体来说就是 \[ \max_{\forall [l,r]}\{\sum_{…

很有趣的一道题吖! 做法:贪心+迭代 Sigma(i*(pr[i]-pr[i-1])))=n-sigma(pr[i]), 所以我们贪心地是pr[i]尽可能大. 也就是让pr[i]/pr[i-1]尽可能大. 这种类型的贪心,和17EC-Final的那个最小化方差的题挺相似的. #include <iostream> #include <algorithm> #include <cstdio> #include <vector> #include <cma…

A. Little Pony and Expected Maximum time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Twilight Sparkle was playing Ludo with her friends Rainbow Dash, Apple Jack and Flutter Shy. But she kept…

http://codeforces.com/problemset/problem/453/A 题目大意: 给定一个m面的筛子,求掷n次后,得到的最大的点数的期望 题解 设f[i]表示掷出 <= i 的点数的概率 ans = sigma{i*(f[i]-f[i-1])} 单个f[i]直接快速幂计算 #include <cstdio> #include <cstring> #include <algorithm> using namespace std; typede…

/* 大连热身D题 题意: 有n个人,m个浴室每个浴室有ai个喷头,每个人等概率得选择一个浴室. 每个浴室的人都在喷头前边排队,而且每个浴室内保证大家都尽可能均匀得在喷头后边排队. 求所有浴室中最长队伍的期望. 思路: 概率dp dp[i][j][k]代表前i个浴室有j个人最长队伍是k的概率. 枚举第i个浴室的人数.然后转移的时候其实是一个二项分布. */ #include<bits/stdc++.h> using namespace std; ]; ][][]; ][]; void init…

Prison Transfer Time Limit: 1000MS   Memory Limit: 262144KB   64bit IO Format: %I64d & %I64u Submit Status Description The prison of your city has n prisoners. As the prison can't accommodate all of them, the city mayor has decided to transfer c of t…

题目地址:http://codeforces.com/contest/459/problem/C C. Pashmak and Buses time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output Recently Pashmak has been employed in a transportation company. The com…

D - Joyful Time Limit:1000MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Description Sakura has a very magical tool to paint walls. One day, kAc asked Sakura to paint a wall that looks like an $M \times N$ matrix. The wal…

1. 利用等概率Rand5生成等概率Rand3 Rand5生成等概率Rand3 这个题目可以扩展为:利用等概率RandM生成等概率RandN (M > N) 这里,我们首先明白一个简单的知识点:如果 randN 可以等概率生成 [0, N) 之间的数 假设 N = T的整倍数,那么我们可以直接使用 RandN() / (N / T) 来等概率生成 [0, T)之间的数 比如说,Rand21可以等概率生成[0, 21)之间的数,那么 Rand21() / 3 就可以等概率生成 [0, 7)之间的数…