[USACO15OPEN]Bessie的生日自助餐Bessie's…

题目描述

For Bessie the cow’s birthday, Farmer John has given her free reign over one of his best fields to eat grass. The field is covered in $N$ patches of grass ($1 \le N \le 1000$), conveniently numbered $1\ldots N$, that each have a distinct quality value. If Bessie eats grass of quality $Q$, she gains $Q$ units of energy. Each patch is connected to up to 10 neighboring patches via bi-directional paths, and it takes Bessie $E$ units of energy to move between adjacent patches ($1 \le E \le 1,000,000$). Bessie can choose to start grazing in any patch she wishes, and she wants to stop grazing once she has accumulated a maximum amount of energy. Unfortunately, Bessie is a picky bovine, and once she eats grass of a certain quality, she’ll never eat grass at or below that quality level again! She is still happy to walk through patches without eating their grass; in fact, she might find it beneficial to walk through a patch of high-quality grass without eating it, only to return later for a tasty snack. Please help determine the maximum amount of energy Bessie can accumulate. 为了庆祝奶牛Bessie的生日,Farmer John给了她一块最好的牧场,让她自由的享用。 牧场上一共有N块草地(1≤N≤1000),编号为1...N,每块草地上牧草的质量都不同。 如果Bessie吃掉的草地上牧草质量为Q,她可以获得Q单位的能量。 每块草地最多和10块草地有相连的道路,在相连的两个草地之间走动需要消耗E单位的能量(1≤E≤1,000,000)。 Bessie可以从任意一块草地开始吃草,并且想要在获得了最多能量的时候停止。 有点遗憾的,Bessie是一头挑食的奶牛,一旦她吃过了一定质量的牧草,她就不会再吃相同或更低质量的牧草!但是她仍然很愿意路过某些草地,而不吃它们。实际上,她发现路过一块高质量的草地而不吃它,等一下返回再去享用,有时会更有利! 请帮忙计算Bessie能够获得的能量的最大值。

输入输出格式

输入格式


The first line of input contains $N$ and $E$. Each of the remaining $N$ lines describe a patch of grass. They contain two integers $Q$ and $D$ giving the quality of the patch (in the range $1\ldots 1,000,000$) and its number of neighbors. The remaining $D$ numbers on the line specify the neighbors. 1行:包含两个整数N和E。 接下来N行:每行描述一块草地,首先两个整数Q和D,分别表示草地上牧草的质量(范围1…1,000,000)和相连的草地数量。然后D个整数表示相连的草地。

输出格式


Please output the maximum amount of energy Bessie can accumulate. 输出Bessie能够获得的能量的最大值。

输入输出样例

输入样例 #1

5 2
4 1 2
1 3 1 3 4
6 2 2 5
5 2 2 5
2 2 3 4

输出样例 #1

7

说明

Bessie starts at patch 4 gaining 5 units of energy from the grass there. She then takes the path to patch 5 losing 2 units of energy during her travel. She refuses to eat the lower quality grass at patch 5 and travels to patch 3 again losing 2 units of energy. Finally she eats the grass at patch 3 gaining 6 units of energy for a total of 7 energy. Note tha the sample case above is different from test case 1 when you submit. 感谢@蒟蒻orz神犇 提供翻译