Cow Marathon
Time Limit:
2000MS |
|
Memory Limit:
30000K |
Total Submissions:
1290 |
|
Accepted:
570 |
Case Time Limit:
1000MS |
Description
After
hearing about the epidemic of obesity in the USA, Farmer John wants his
cows to get more exercise, so he has committed to create a bovine
marathon for his cows to run. The marathon route will include a pair of
farms and a path comprised of a sequence of roads between them. Since
FJ wants the cows to get as much exercise as possible he wants to find
the two farms on his map that are the farthest apart from each other
(distance being measured in terms of total length of road on the path
between the two farms). Help him determine the distances between this
farthest pair of farms.
Input
* Lines 1.....: Same input format as "Navigation Nightmare".
Output
* Line 1: An integer giving the distance between the farthest pair of farms.
Sample Input
7 6
1 6 13 E
6 3 9 E
3 5 7 S
4 1 3 N
2 4 20 W
4 7 2 S
Sample Output
52
Hint
The longest marathon runs from farm 2 via roads 4, 1, 6 and 3 to farm 5 and is of length 20+3+13+9+7=52.
Source
题目大意:
在一颗树上找到两个点的距离的最大值。
就是经典的树形dp,不过调试了多久呢,将近两天,是一个小错误,看了很久就是没发现,重新写了一下以前的代码才突然想到的。。。
这样的效率不好!一鼓作气!