Problem 3: Nearby Cows [Neal Wu and Eric Price, 2011]
Farmer John has noticed that his cows often move between nearby fields.
Taking this into account, he wants to plant enough grass in each of his
fields not only for the cows situated initially in that field, but also for
cows visiting from nearby fields.
Specifically, FJ's farm consists of N fields (1 <= N <= 100,000), where
some pairs of fields are connected with bi-directional trails (N-1 of them
in total). FJ has designed the farm so that between any two fields i and
j, there is a unique path made up of trails connecting between i and j.
Field i is home to C(i) cows, although cows sometimes move to a different
field by crossing up to K trails (1 <= K <= 20).
FJ wants to plant enough grass in each field i to feed the maximum number
of cows, M(i), that could possibly end up in that field -- that is, the
number of cows that can potentially reach field i by following at most K
trails. Given the structure of FJ's farm and the value of C(i) for each
field i, please help FJ compute M(i) for every field i.
PROBLEM NAME: nearcows
* Line 1: Two space-separated integers, N and K.
* Lines 2..N: Each line contains two space-separated integers, i and j
(1 <= i,j <= N) indicating that fields i and j are directly
connected by a trail.
* Lines N+1..2N: Line N+i contains the integer C(i). (0 <= C(i) <=
SAMPLE INPUT (file nearcows.in):
There are 6 fields, with trails connecting (5,1), (3,6), (2,4), (2,1), and
(3,2). Field i has C(i) = i cows.
* Lines 1..N: Line i should contain the value of M(i).
SAMPLE OUTPUT (file nearcows.out):
Field 1 has M(1) = 15 cows within a distance of 2 trails, etc.