After a long party Petya decided to return home, but he turned out to be at the opposite end of the town from his home. There are nn crossroads in the line in the town, and there is either the bus or the tram station at each crossroad. The crossroads…

Codeforces 1165F1/F2 二分好题 传送门:https://codeforces.com/contest/1165/problem/F2 题意: 有n种物品,你对于第i个物品,你需要买\(k_i\)个,每个物品在非打折日买是2块钱,在打折日买是1块钱,每天你可以赚一块钱,现在告诉你一共有m个打折日,在第\(d_i\)天第\(t_i\)种物品打折,问你你最少需要多少天可以买完你需要的物品 题解: 二分 思路是这样的 根据题目的题意,你最多打工4e5天就可以买完所有的物品,所以我们可…

题目链接:http://codeforces.com/contest/732/problem/D 题意:有m门需要过的课程,n天的时间可以选择复习.考试(如果的d[i]为0则只能复习),一门课至少要复习a[i]天才能通过,问最早什么时候可以把所有课程都通过,如果不能输出-1. 思路:二分判断,比赛时不会check...具体见注释. #include<bits/stdc++.h> using namespace std; const int N = 1e5 + 5; int n,m,d[N],a…

题目链接: http://acm.hust.edu.cn/vjudge/problem/viewProblem.action?id=47319 题目大意:给定一个序列,要求确定一个子序列,①使得该子序列中所有值都能被其中一个值整除,②且子序列范围尽可能大(r-l尽可能大). 解题思路: 对于要求1,不难发现只有min(L,R)=gcd(L,R)时才行.其中gcd是L,R范围内的最大公约数,min是L,R范围内的最小值. 对于要求2,传统思路是r-l从大到小枚举,每次确定一个(L,R)范围,进行判…

Lemmings 题目连接: http://codeforces.com/contest/163/problem/B Descriptionww.co As you know, lemmings like jumping. For the next spectacular group jump n lemmings gathered near a high rock with k comfortable ledges on it. The first ledge is situated at t…

题目链接:http://codeforces.com/problemset/problem/589/F 题目大意:一位美食家进入宴会厅,厨师为客人提供了n道菜.美食家知道时间表:每个菜肴都将供应. 对于第i道菜肴,他知道时间ai和bi的两个整数时刻(从宴会开始的几秒钟内) - ai为该菜端出来的时间,bi为该菜端走的时间(ai <BI).例如,如果ai = 10且bi = 11,那么第i个菜肴可在一秒钟内进食. 菜肴数量非常大,所以只要菜肴可以吃(即,在大厅里),它就无法用完. 美食家想要尝试每…

There are n people and k keys on a straight line. Every person wants to get to the office which is located on the line as well. To do that, he needs to reach some point with a key, take the key and then go to the office. Once a key is taken by somebo…

链接:CodeForces - 1059D 题意:给出笛卡尔坐标系上 n 个点,求与 x 轴相切且覆盖了所有给出点的圆的最小半径. 题解:二分半径即可.判断:假设当前二分到的半径是 R ,因为要和 x 轴相切,所以圆心一定在 y = R 上,对于每一个点而言,圆要覆盖该点,那么圆心在 y = R 上一定有一段限定区间,所以只要判断这 n 个区间是否有公共区间即可.卡点:误差,太可恶了,求区间段时应该将 sqrt(R * R - d * d) 写成 sqrt(R - d) * sqrt(R + d…

Time limit4000 ms Memory limit262144 kB There are nn dormitories in Berland State University, they are numbered with integers from 11 to nn. Each dormitory consists of rooms, there are aiai rooms in ii-th dormitory. The rooms in ii-th dormitory are n…

题面: 传送门:http://codeforces.com/problemset/problem/475/D Given a sequence of integers a1, -, an and q queries x1, -, xq on it. For each query xi you have to count the number of pairs (l, r) such that 1 ≤ l ≤ r ≤ n and gcd(al, al + 1, -, ar) = xi. 题目大意:…