【BZOJ】1620: [Usaco2008 Nov]Time Management 时间管理(贪心)

http://www.lydsy.com/JudgeOnline/problem.php?id=1620

一开始想不通啊。。

其实很简单。。。

每个时间都有个完成时间,那么我们就从最大的 完成时间的开始往前推

每一次更新最早开始时间(min(ans, a[i].y)代表i事件最早的完成时间)

 

 


 

 

Description

Ever the maturing businessman, Farmer John realizes that he must manage his time effectively. He has N jobs conveniently numbered 1..N (1 <= N <= 1,000) to accomplish (like milking the cows, cleaning the barn, mending the fences, and so on). To manage his time effectively, he has created a list of the jobs that must be finished. Job i requires a certain amount of time T_i (1 <= T_i <= 1,000) to complete and furthermore must be finished by time S_i (1 <= S_i <= 1,000,000). Farmer John starts his day at time t=0 and can only work on one job at a time until it is finished. Even a maturing businessman likes to sleep late; help Farmer John determine the latest he can start working and still finish all the jobs on time.

N个工作,每个工作其所需时间,及完成的Deadline,问要完成所有工作,最迟要什么时候开始.

Input

* Line 1: A single integer: N

* Lines 2..N+1: Line i+1 contains two space-separated integers: T_i and S_i

Output

* Line 1: The latest time Farmer John can start working or -1 if Farmer John cannot finish all the jobs on time.

Sample Input

4
3 5
8 14
5 20
1 16

INPUT DETAILS:

Farmer John has 4 jobs to do, which take 3, 8, 5, and 1 units of
time, respectively, and must be completed by time 5, 14, 20, and
16, respectively.

Sample Output

2

OUTPUT DETAILS:

Farmer John must start the first job at time 2. Then he can do
the second, fourth, and third jobs in that order to finish on time.

HINT

Source

posted @   iwtwiioi  阅读(350)  评论(0编辑  收藏  举报
编辑推荐:
· AI与.NET技术实操系列:基于图像分类模型对图像进行分类
· go语言实现终端里的倒计时
· 如何编写易于单元测试的代码
· 10年+ .NET Coder 心语,封装的思维:从隐藏、稳定开始理解其本质意义
· .NET Core 中如何实现缓存的预热?
阅读排行:
· 25岁的心里话
· 闲置电脑爆改个人服务器(超详细) #公网映射 #Vmware虚拟网络编辑器
· 基于 Docker 搭建 FRP 内网穿透开源项目(很简单哒)
· 零经验选手,Compose 一天开发一款小游戏!
· 一起来玩mcp_server_sqlite,让AI帮你做增删改查!!
点击右上角即可分享
微信分享提示