Submission #690130

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Source Code Expand

b = gets.to_s.chomp.to_i#split(" ").map(&:to_i)
a = {} #of Int32 => Array(Int32)
(b-1).times do
  t = gets.to_s.chomp.split(" ").map{|s| s.to_i}
  a[t[0]] = [] unless a[t[0]]#?
  a[t[0]] << t[1]
  
  a[t[1]] = [] unless a[t[1]]#?
  a[t[1]] << t[0]
end

B = [*0..b].map {0}
W = [*0..b].map {0}
 
def dfs(num,prev, a)
  B[num]=1
  W[num]=1
  a[num].each do |r|
    next if r == prev
    dfs(r, num,a)
    W[num] = W[num]*(W[r]+B[r])% 1000000007
    B[num] = B[num]*W[r]% 1000000007
  end
end

dfs(1,0,a)
p (W[1]+B[1])%1000000007

Submission Info

Judge Result