Laskettelukeskus

class Node
  def initialize(parent, required)
    @parent = parent
    @required = required
    @children = []
    @total = 0
  end

  def make(required)
    n = Node.new(self, 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

count = gets.chomp.to_i

rows = [[1, 1]]
(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

root = Node.new(nil, requireds[0])
rows = rows[1..-1].sort_by { |x| x[0] }
nodes = {1 => root}
rows.each do |a, b, r|
  nodes[b] = nodes[a].make(r)
end

puts root.go_down

Test 1

Group: 1, 2

Verdict: ACCEPTED

Test 2

Group: 1, 2

Verdict: RUNTIME ERROR

input/code.rb:40:in `block in <main>': undefined method `make' for nil:NilClass (NoMethodE...

Test 3

Group: 1, 2

Verdict: RUNTIME ERROR

input/code.rb:40:in `block in <main>': undefined method `make' for nil:NilClass (NoMethodE...

Test 4

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:40:in `block in <main>': undefined method `make' for nil:NilClass (NoMethodE...

Test 5

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:40:in `block in <main>': undefined method `make' for nil:NilClass (NoMethodE...

Test 6

Group: 1, 2

Verdict: RUNTIME ERROR

input/code.rb:40:in `block in <main>': undefined method `make' for nil:NilClass (NoMethodE...

Test 7

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:40:in `block in <main>': undefined method `make' for nil:NilClass (NoMethodE...

Test 8

Group: 1, 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: RUNTIME ERROR

input/code.rb:16:in `block in go_down': stack level too deep (SystemStackError)
	from inpu...

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