Laskettelukeskus

# memory optimization
#class Node
#  def initialize(required)
#    @required = required
#    @children = []
#    @total = 0
#  end
# 
#  def make(required)
#    n = Node.new(required)
#    @children << n
#    return n
#  end
#
#  def go_down
#    @children.each { |child| @total += child.go_down }
#    if @required > @total
#      @total = @required
#    end
#    return @total
#  end
#end

class Array
  def go_down(nodes)
    self[0].each { |child| self[2] += nodes[child].go_down(nodes) }
    if self[1] > self[2]
      self[2] = self[1]
    end
    #puts("going up, t=#{self[2]}")
    self[2]
  end
#  def go_down
#    @children.each { |child| @total += child.go_down }
#    if @required > @total
#      @total = @required
#    end
#    return @total
#  end
end

count = gets.chomp.to_i
 
rows = [[0, 0]]
(count - 1).times do
  rows << gets.chomp.split(" ").map(&:to_i)
end
 
requireds = gets.chomp.split(" ").map(&:to_i)
requireds.each_with_index do |r, i|
  rows[i] << r
end
rows = rows.sort_by { |x| x[0] }
# Node = [[children], required, count]
root = [[], rows[0][2], 0]
nodes = {1 => root}
rows.each do |a, b, r|
  nodes[b] = [[], r, 0]
  nodes[a][0] << b
end
 
puts root.go_down(nodes)

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: RUNTIME ERROR

input/code.rb:59:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodErr...

Test 3

Group: 1, 2

Verdict: RUNTIME ERROR

input/code.rb:59:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodErr...

Test 4

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:59:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodErr...

Test 5

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:59:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodErr...

Test 6

Group: 1, 2

Verdict: RUNTIME ERROR

input/code.rb:59:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodErr...

Test 7

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:59:in `block in <main>': undefined method `[]' for nil:NilClass (NoMethodErr...

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:26:in `go_down': stack level too deep (SystemStackError)
	from input/code.rb...

Test 10

Group: 1, 2

Verdict: ACCEPTED

Test 11

Group: 2

Verdict: ACCEPTED

Test 12

Group: 1, 2

Verdict: ACCEPTED

Test 13

Group: 2

Verdict: ACCEPTED