天下一プログラマーコンテスト2016 [AtCoder] [Ruby]

tenka1-2016-qualA-a.rb

res = 0
(1..100).each do |i|
  if (i % 3 != 0) && (i % 5 != 0) then
    res += i
  end
end
puts res

tenka1-2016-qualA-b.rb

# ref: http://tenka1-2016-quala.contest.atcoder.jp/submissions/827678
node = Struct.new("Node", :parent, :children, :value)
n, m = gets.chomp.split(" ").map(&:to_i)
@graph = Array.new(n){node.new(-1, [], 0)}
1.upto(n-1).each do |i|
  parent = gets.chomp.to_i
  @graph[i][:parent] = parent
  @graph[parent][:children] = @graph[parent][:children].push(i)
end
m.times do
  b, c = gets.chomp.split(" ").map(&:to_i)
  @graph[b][:value] = c
end

def dfs(node)
  s = node.children.map{|e| dfs(@graph[e])}
  if node.parent == -1 then
    y = 0
  else
    y = node.children.map{|e| @graph[e].value}.min || 0
  end
  node[:value] = node[:value] + y
  return s.inject(node.value){|s, e| s + (e - y)}
end
puts dfs(@graph[0])