题目链接: http://codeforces.com/problemset/problem/268/E E. Playlist time limit per test 1 secondmemory limit per test 256 megabytes 问题描述 Manao's friends often send him new songs. He never listens to them right away. Instead, he compiles them into a play…

题目大意 给定一个1到n的排列,然后随机选取一个区间,让这个区间内的数随机改变顺序,问这样的一次操作后,该排列的逆序数的期望是多少 首先,一个随机的长度为len的排列的逆序数是(len)*(len-1)/4,这是显然的,因为每种排列倒序一遍就会得到一个新序列,逆序数是len*(len-1)/2 - x(x为原排列的逆序数) 所以我们只需要把所有n*(n-1)/2的区间每种情况都随机化一遍再求逆序对,然后把这个值求和,就可以得到答案了 但是如果用朴素做法,那么复杂度是n^2的 考虑dp[x]表示以…

Hard problem 题目链接: http://codeforces.com/contest/706/problem/C Description Vasiliy is fond of solving different tasks. Today he found one he wasn't able to solve himself, so he asks you to help. Vasiliy is given n strings consisting of lowercase Engl…

B. Dreamoon and WiFi 题目连接: http://www.codeforces.com/contest/476/problem/B Description Dreamoon is standing at the position 0 on a number line. Drazil is sending a list of commands through Wi-Fi to Dreamoon's smartphone and Dreamoon follows them. Eac…

A. Mafia Time Limit: 20 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/348/problem/A Description One day n friends gathered together to play "Mafia". During each round of the game some player must be the supervisor and other n - 1…

A. Games 模拟. B. Buttons 简单计数. C. Beautiful Sets of Points 显然每行每列只能有一个点,那么最大点数为\(1+min(n, m)\). 在不考虑\(x,y\gt 0\)的条件下,直接沿着主对角线放点即可,由于该条件限制,则沿副对角线放置即可. D. Wall Bars 详细的官方题解 主要考虑每根柱子最后位置的DP. E. Playlist 位置i的贡献值为\[l_i+(1-p_i)\sum_{j=1}^{i-1}{l_jp_j}\] 考虑贪…

B. Urbanization 题目链接 http://codeforces.com/contest/735/problem/B 题面 Local authorities have heard a lot about combinatorial abilities of Ostap Bender so they decided to ask his help in the question of urbanization. There are n people who plan to move…

B. Sail 题目连接: http://www.codeforces.com/contest/298/problem/B Description The polar bears are going fishing. They plan to sail from (sx, sy) to (ex, ey). However, the boat can only sail by wind. At each second, the wind blows in one of these directio…

A. Purification Time Limit: 20 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/329/problem/A Description You are an adventurer currently journeying inside an evil temple. After defeating a couple of weak zombies, you arrived at a square r…

A. Exams Time Limit: 1 Sec Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/480/problem/A Description Student Valera is an undergraduate student at the University. His end of term exams are approaching and he is to pass exactly n exams. Valera…

B. Passwords 题目连接: http://codeforces.com/contest/721/problem/B Description Vanya is managed to enter his favourite site Codehorses. Vanya uses n distinct passwords for sites at all, however he can't remember which one exactly he specified during Code…

E. Trains and Statistic 题目连接: http://www.codeforces.com/contest/675/problem/E Description Vasya commutes by train every day. There are n train stations in the city, and at the i-th station it's possible to buy only tickets to stations from i + 1 to a…

C. Woodcutters Time Limit: 20 Sec  Memory Limit: 256 MB 题目连接 http://codeforces.com/contest/545/problem/C Description Little Susie listens to fairy tales before bed every day. Today's fairy tale was about wood cutters and the little girl immediately s…

http://codeforces.com/contest/732/problem/D 这题我发现很多人用二分答案,但是是不用的. 我们统计一个数值all表示要准备考试的所有日子和.+m(这些时间用来考试) 那么这个all值就是理想的最小值.然后去前all个数找,贪心地复习最小的科目,然后有的考试的话,就优先考试. 如果经过这all天,复习完了(这个是肯定得),但是只是因为时间分配不好,导致没得考试(数据导致没得考试) 那么就暴力枚举后面的[all + 1, n].有得考试就去考试,刚好考完就直…

链接: https://codeforces.com/contest/1216/problem/B 题意: Recently Vasya decided to improve his pistol shooting skills. Today his coach offered him the following exercise. He placed n cans in a row on a table. Cans are numbered from left to right from 1…

https://codeforces.com/contest/1256 A:Payment Without Change[思维] 题意:给你a个价值n的物品和b个价值1的物品,问是否存在取物方案使得价值为s 题解:min(s/n,a)*n+b>=s?YES:NO #include<iostream> #include<cstdio> #include<cstdlib> #include<cmath> #include<algorithm>…

题目:http://codeforces.com/contest/1185/problem/G1 题意:给你n给选项,每个选项有个类型和价值,让你选择一个序列,价值和为m,要求连续的不能有两个相同的类型,相同的物]品不一样的顺序代表不同,问有多少个序列 思路:首先范围是15个,这里我们可以用状压来代表选择哪些物品,然后这里是说不能有连续相同的类型,这里我们贪心考虑不全,最开始我考虑的是组合数的插空法,当时 发现有很多细节,写不了,这样的话我们就只能改成dp, 我们设置dp[i][j]   代表i…

题目:Click here 题意:给你n,然后n个数,n个数中可能重复,可能不是1到n中的数.然后你用最少的改变数,让这个序列包含1到n所有数,并输出最后的序列. 分析:贪心. #include <bits/stdc++.h> using namespace std; ; int n; int a[M]; // 给定序列 int mark[M]; // mark[i] 表示i在给定序列中的出现次数 int notap[M]; // 给的序列中没有出现的元素 bool firstout; voi…

D. Diverse Garland time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output You have a garland consisting of nn lamps. Each lamp is colored red, green or blue. The color of the ii-th lamp is sisi ('…

贪心的选取最优解 然后相减好 记得要开long long #include <cstdio> #include <algorithm> #include <cstring> #include <set> #include <queue> #define int long long using namespace std; ,ansb=,posa=,posb=,n,a[],b[]; bool cmp(int a,int b){ if(a>b)…

题目链接:http://www.codeforces.com/problemset/problem/268/A题意:足球比赛中如果主场球队的主场球衣和客队的客队球衣颜色一样,那么要求主队穿上他们的可对球衣,现在有n个球队,每一球队的主场球衣和客场球衣的颜色都告诉你了,它们两两之间要比一场赛.求其中主队穿客场球衣的比赛场数.C++代码: #include <iostream> using namespace std; ; int x[maxn], y[maxn], n, ans; int mai…

There are n workers in a company, each of them has a unique id from 1 to n. Exaclty one of them is a chief, his id is s. Each worker except the chief has exactly one immediate superior. There was a request to each of the workers to tell how how many…

orz 最近被水题卡+FST,各种掉rating 题目大意 一个数s它是n进制的,但是每一位不是用'A','B'....表示的,而是用10,11等等表示的,将它还原成十进制 这种表示方法显然会产生多解,然后求所有的解中最小的那个 这题一想就是贪心,但是一开始算法写渣了,改变思路以后才A的 简单来说就是从右边开始,把尽量多的数压到一位里面,这样会使数更小 压的思路可以这么考虑 每次新加进来一个数,如果加进来以后,已经大于原来的那个数,那么就找截取一段可行的最大数 这样考虑的目的是处理前导0带来的影…

#include<bits/stdc++.h>using namespace std;int mi[100007];int main(){ int cnt=0; int flag=0; int ans=1; int n,k=0; scanf("%d",&n); for(int i=2;i*i<=n;i++){ if(n%i==0){ flag=1; break; } } if(flag==0)//如果不用操作直接输出即可 printf("%d %d&…

题目链接:http://codeforces.com/problemset/problem/545/D 题解: 问经过调整,最多能使多少个人满意. 首先是排序,然后策略是:如果这个人对等待时间满意,则将其加入队伍中,更新当前的等候时间:如果不满意,既然等待时间最小了都不满意,那把他扔到最后,即跳过他,接着考虑下一个. 代码如下: #include<cstdio>//F - F CodeForces - 545D #include<cstring> #include<cstdl…

E. Arthur and Brackets time limit per test 2 seconds memory limit per test 128 megabytes input standard input output standard output Notice that the memory limit is non-standard. Recently Arthur and Sasha have studied correct bracket sequences. Arthu…

传送门 D. Handshakes time limit per test 1 second memory limit per test 256 megabytes input standard input output standard output On February, 30th n students came in the Center for Training Olympiad Programmers (CTOP) of the Berland State University. T…

A. Bits   Let's denote as  the number of bits set ('1' bits) in the binary representation of the non-negative integer x. You are given multiple queries consisting of pairs of integers l and r. For each query, find the x, such that l ≤ x ≤ r, and is m…

http://codeforces.com/contest/1154/problem/D 解题: 1.无光的时候优先使用太阳能电池. 2.有光的时候 (1)太阳能电池没满电,让它充,使用普通电池 (2)太阳能电池满电,使用太阳能电池 #include<stdio.h> #include<math.h> #include<string.h> #include<algorithm> #include<string> #include<vecto…

构造两颗深度为30的字典树(根节点分别是0和1),结点只有0和1,从根节点向下DFS,贪心取答案. #define HAVE_STRUCT_TIMESPEC #include<bits/stdc++.h> using namespace std; vector<int>a; int dfs(vector<int>b,int x){ ||b.size()==)//30位都枚举完毕或当前向量中没有数字就中止 ; vector<int>c,d; ;i<b.s…