题目链接 感觉这题很裸啊,除了看着恶心点也没什么了,怎么过的人那么少.. \(Description\) 给定\(n,r,s\),表示有\(n\)个人,设每个人的得分是非负整数\(a_i\),已知第一个人的得分\(a_1\geq r\),所有人的得分之和\(\sum a_i=s\).得分最高的一个人获胜:若有多个人得分最高,则随机一个人获胜. 求在所有可能情况下,第一个人获胜的概率. \(n\leq100,\ 0\leq r\leq s\leq5000\). \(Solution\) 范围不是很…

一道经典组合数学+容斥题. 题目传送门:CF1096E. 题意简述: \(p\) 个人,每个人有得分 \(a_i\). 总得分 \(\sum a_i = s\). 第一个人得分 \(a_1 \ge r\). 得分最高的人可以获胜,如果多个人得分最高,则等概率随机其中一个人获胜. 问第一个人获胜的概率. 题解: 第一个人要获胜,他的得分必须是最高分. 考虑枚举第一个人的得分,假设 \(a_1 = x\). 再枚举总共有几个人得分和第一个人一样(包括第一个人),假设有 \(i\) 个. 那么剩下的…

Codeforces 932E Team work You have a team of N people. For a particular task, you can pick any non-empty subset of people. The cost of having x people for the task is xk. Output the sum of costs over all non-empty subsets of people. Input Only line o…

I - Parking Lot Time Limit:500MS     Memory Limit:65536KB     64bit IO Format:%I64d & %I64u Submit Status Description To quickly hire highly skilled specialists one of the new IT City companies made an unprecedented move. Every employee was granted a…

#include <iostream> #include <cstdio> #include<cmath> #include<algorithm> using namespace std; ]; void init_arrary(){ ; i <= ; ++i) { num[i] = num[i - ] + log(i); } } double Cn(int m,int n){ return num[m] - num[n] - num[m-n]; }…

题目地址:洛谷CF1096E 本场AC数最少 (最难) 的题目 题目大意:给出三个数p , s,r,表示有p人,每个人都有一个非负得分,所有人的得分和为s,Hasan的得分至少为r,求Hasan是第一的概率(得分相同的人名次是等概率分布) 数据范围: \(1 \leq p \leq 100,0 \leq r \leq s \leq 5000\) 注意输出有一个整数化处理:若 \(ans = \frac{P}{Q}\) ,输出 \(P \times inv_Q(mod\ 998244353)\)…

题目链接: B. Spider Man time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output Peter Parker wants to play a game with Dr. Octopus. The game is about cycles. Cycle is a sequence of vertices, such that…

题目链接: F. Couple Cover time limit per test 3 seconds memory limit per test 512 megabytes input standard input output standard output Couple Cover, a wildly popular luck-based game, is about to begin! Two players must work together to construct a recta…

题目描述: You are given an array consisting of nmonotonic renumeration as an array b consisting of \(n\)integers such that all of the following conditions are met: b1=0; for every pair of indices iand jsuch that 1≤i,j≤n, then \(b_i=b_j\), it is still pos…

D. Basketball Team time limit per test 2 seconds memory limit per test 256 megabytes input standard input output standard output As a German University in Cairo (GUC) student and a basketball player, Herr Wafa was delighted once he heard the news. GU…