POJ 1922 Ride to School C语言版

POJ题解 2087浏览

Description

Many graduate students of Peking University are living in Wanliu Campus, which is 4.5 kilometers from the main campus – Yanyuan. Students in Wanliu have to either take a bus or ride a bike to go to school. Due to the bad traffic in Beijing, many students choose to ride a bike.

We may assume that all the students except "Charley" ride from Wanliu to Yanyuan at a fixed speed. Charley is a student with a different riding habit – he always tries to follow another rider to avoid riding alone. When Charley gets to the gate of Wanliu, he will look for someone who is setting off to Yanyuan. If he finds someone, he will follow that rider, or if not, he will wait for someone to follow. On the way from Wanliu to Yanyuan, at any time if a faster student surpassed Charley, he will leave the rider he is following and speed up to follow the faster one.

We assume the time that Charley gets to the gate of Wanliu is zero. Given the set off time and speed of the other students, your task is to give the time when Charley arrives at Yanyuan.

Input

There are several test cases. The first line of each case is N (1 <= N <= 10000) representing the number of riders (excluding Charley). N = 0 ends the input. The following N lines are information of N different riders, in such format:

Vi [TAB] Ti

Vi is a positive integer <= 40, indicating the speed of the i-th rider (kph, kilometers per hour). Ti is the set off time of the i-th rider, which is an integer and counted in seconds. In any case it is assured that there always exists a nonnegative Ti.

Output

Output one line for each case: the arrival time of Charley. Round up (ceiling) the value when dealing with a fraction.

Sample Input

4
20    0
25    -155
27    190
30    240
2
21    0
22    34
0

Sample Output

780
771

Slyar:说下题目大意。大概就是说一个叫Charley的人在0秒的时候在Wanliu门口等同学骑单车载他去Yanyuan(题目中给出其他单车的速度以及出发时间)，当有其他单车超过Charley时，他会跳上那辆快车继续前进，问最后Charley用了多长时间到达Yanyuan。

网友最新评论 (3)

1. 请问min=4.5*3600是什么意思
编程小白1年前 (2017-07-11)回复
2. @熟人Y 呵呵，Ylemzy，又换马甲了？
Slyar9年前 (2009-09-01)回复
3. 精度问题还是难以理解。我用 v /= 3.6; time += 4500.0 / v + t; 结果WR。
熟人Y9年前 (2009-09-01)回复