Codeforces Round 497 (Div. 1)
E
Mini Metro
Codeforces
3400
原题
← D→
翻译中…

In a simplified version of a "Mini Metro" game, there is only one subway line, and all the trains go in the same direction. There are $n$ stations on the line, $a_i$ people are waiting for the train at the $i$-th station at the beginning of the game. The game starts at the beginning of the $0$-th hour. At the end of each hour (couple minutes before the end of the hour), $b_i$ people instantly arrive to the $i$-th station. If at some moment, the number of people at the $i$-th station is larger than $c_i$, you lose.

翻译中…

A player has several trains which he can appoint to some hours. The capacity of each train is $k$ passengers. In the middle of the appointed hour, the train goes from the $1$-st to the $n$-th station, taking as many people at each station as it can accommodate. A train can not take people from the $i$-th station if there are people at the $i-1$-th station.

翻译中…

If multiple trains are appointed to the same hour, their capacities are being added up and they are moving together.

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The player wants to stay in the game for $t$ hours. Determine the minimum number of trains he will need for it.

翻译中…

Input

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The first line contains three integers $n$, $t$, and $k$ ($1 \leq n, t \leq 200, 1 \leq k \leq 10^9$) — the number of stations on the line, hours we want to survive, and capacity of each train respectively.

翻译中…

Each of the next $n$ lines contains three integers $a_i$, $b_i$, and $c_i$ ($0 \leq a_i, b_i \leq c_i \leq 10^9$) — number of people at the $i$-th station in the beginning of the game, number of people arriving to $i$-th station in the end of each hour and maximum number of people at the $i$-th station allowed respectively.

翻译中…

Output

翻译中…

Output a single integer number — the answer to the problem.

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Note

翻译中…

image

翻译中…

Let's look at the sample. There are three stations, on the first, there are initially 2 people, 3 people on the second, and 4 people on the third. Maximal capacities of the stations are 10, 9, and 8 respectively.

翻译中…

One of the winning strategies is to appoint two trains to the first and the third hours. Then on the first hour, the train takes all of the people from the stations, and at the end of the hour, 4 people arrive at the first station, 3 on the second, and 2 on the third.

翻译中…

In the second hour there are no trains appointed, and at the end of it, the same amount of people are arriving again.

翻译中…

In the third hour, the train first takes 8 people from the first station, and when it arrives at the second station, it takes only 2 people because it can accommodate no more than 10 people. Then it passes by the third station because it is already full. After it, people arrive at the stations once more, and the game ends.

翻译中…

As there was no such moment when the number of people at a station exceeded maximal capacity, we won using two trains.

翻译中…

样例

Input #1
3 3 10
2 4 10
3 3 9
4 2 8
Output #1
2
InputCopy OutputCopy
Input #2
4 10 5
1 1 1
1 0 1
0 5 8
2 7 100
Output #2
12
InputCopy OutputCopy
题目信息
题号
1007E
时间限制
2 s
内存限制
256 MB
标签
动态规划

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。