[Usaco2014 Dec]Guard Mark

题目描述

Farmer John and his herd are playing frisbee. Bessie throws the frisbee down the field, but it's going straight to Mark the field hand on the other team! Mark has height H (1 <= H <= 1,000,000,000), but there are N cows on Bessie's team gathered around Mark (2 <= N <= 20). They can only catch the frisbee if they can stack up to be at least as high as Mark. Each of the N cows has a height, weight, and strength. A cow's strength indicates the maximum amount of total weight of the cows that can be stacked above her. Given these constraints, Bessie wants to know if it is possible for her team to build a tall enough stack to catch the frisbee, and if so, what is the maximum safety factor of such a stack. The safety factor of a stack is the amount of weight that can be added to the top of the stack without exceeding any cow's strength.
给出N头牛，每头牛有自己的高度，自身重量及承受重量。 现在从N头牛中选出一些牛来，叠成一堆。问是否可以达到一个高度为H的值。

输入格式

输出格式

样例输入

4 10
9 4 1
3 3 5
5 5 10
4 4 5

样例输出

2

提示

没有写明提示

题目来源

Gold