Codeforces Round 707 (Div. 2, based on Moscow Open Olympiad in Informatics)
A
Alexey and Train
Codeforces
800
原题
←B →
翻译中…

Alexey is travelling on a train. Unfortunately, due to the bad weather, the train moves slower that it should!

翻译中…

Alexey took the train at the railroad terminal. Let's say that the train starts from the terminal at the moment $0$. Also, let's say that the train will visit $n$ stations numbered from $1$ to $n$ along its way, and that Alexey destination is the station $n$.

翻译中…

Alexey learned from the train schedule $n$ integer pairs $(a_i, b_i)$ where $a_i$ is the expected time of train's arrival at the $i$-th station and $b_i$ is the expected time of departure.

翻译中…

Also, using all information he has, Alexey was able to calculate $n$ integers $tm_1, tm_2, \dots, tm_n$ where $tm_i$ is the extra time the train need to travel from the station $i - 1$ to the station $i$. Formally, the train needs exactly $a_i - b_{i-1} + tm_i$ time to travel from station $i - 1$ to station $i$ (if $i = 1$ then $b_0$ is the moment the train leave the terminal, and it's equal to $0$).

翻译中…

The train leaves the station $i$, if both conditions are met:

翻译中…
  1. it's on the station for at least $\left\lceil \frac{b_i - a_i}{2} \right\rceil$ units of time (division with ceiling);
  2. current time $\ge b_i$.
翻译中…

Since Alexey spent all his energy on prediction of time delays, help him to calculate the time of arrival at the station $n$.

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Input

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The first line contains one integer $t$ ($1 \le t \le 100$) — the number of test cases.

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The first line of each test case contains the single integer $n$ ($1 \le n \le 100$) — the number of stations.

翻译中…

Next $n$ lines contain two integers each: $a_i$ and $b_i$ ($1 \le a_i \lt b_i \le 10^6$). It's guaranteed that $b_i \lt a_{i+1}$.

翻译中…

Next line contains $n$ integers $tm_1, tm_2, \dots, tm_n$ ($0 \le tm_i \le 10^6$).

翻译中…

Output

翻译中…

For each test case, print one integer — the time of Alexey's arrival at the last station.

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Note

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In the first test case, Alexey arrives at station $1$ without any delay at the moment $a_1 = 2$ (since $tm_1 = 0$). After that, he departs at moment $b_1 = 4$. Finally, he arrives at station $2$ with $tm_2 = 2$ extra time, or at the moment $12$.

翻译中…

In the second test case, Alexey arrives at the first station with $tm_1 = 1$ extra time, or at moment $2$. The train, from one side, should stay at the station at least $\left\lceil \frac{b_1 - a_1}{2} \right\rceil = 2$ units of time and from the other side should depart not earlier than at moment $b_1 = 4$. As a result, the trains departs right at the moment $4$.

翻译中…

Using the same logic, we can figure out that the train arrives at the second station at the moment $9$ and departs at the moment $10$; at the third station: arrives at $14$ and departs at $15$; at the fourth: arrives at $22$ and departs at $23$. And, finally, arrives at the fifth station at $32$.

翻译中…

样例

Input #1
2
2
2 4
10 12
0 2
5
1 4
7 8
9 10
13 15
19 20
1 2 3 4 5
Output #1
12
32
InputCopy OutputCopy
题目信息
题号
1501A
时间限制
1 s
内存限制
256 MB
标签
模拟

题面与样例版权归 Codeforces 及出题人所有;中文翻译由 AI 生成(CI 管线),如有出入请以原文为准。