OpenJudge

I:Rebuilding Roads

总时间限制:
1000ms
内存限制:
65536kB
描述
The cows have reconstructed Farmer John's farm, with its N barns (1 <= N <= 150, number 1..N) after the terrible earthquake last May. The cows didn't have time to rebuild any extra roads, so now there is exactly one way to get from any given barn to any other barn. Thus, the farm transportation system can be represented as a tree.

Farmer John wants to know how much damage another earthquake could do. He wants to know the minimum number of roads whose destruction would isolate a subtree of exactly P (1 <= P <= N) barns from the rest of the barns.
输入
* Line 1: Two integers, N and P

* Lines 2..N: N-1 lines, each with two integers I and J. Node I is node J's parent in the tree of roads.
输出
A single line containing the integer that is the minimum number of roads that need to be destroyed for a subtree of P nodes to be isolated.
样例输入
11 6
1 2
1 3
1 4
1 5
2 6
2 7
2 8
4 9
4 10
4 11
样例输出
2
提示
[A subtree with nodes (1, 2, 3, 6, 7, 8) will become isolated if roads 1-4 and 1-5 are destroyed.]
来源
USACO 2002 February

F题:雷达站的坐标需要是double类型而不是int类型
E题:重要逆序对的最后结果请用int型存储
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全局题号
949
提交次数
7
尝试人数
3
通过人数
1