Submission #57364754

---

Source Code Expand

def main
    n, k = gets.chomp.split.map(&:to_i)
    
    e = Array.new(n) { [] }
    (n - 1).times do
        a, b = gets.chomp.split.map(&:to_i)
        a -= 1
        b -= 1
        e[a] << b
        e[b] << a
    end

    v = gets.chomp.split.map(&:to_i).map { |x| x - 1 }

    par = Array.new(n, -1)
    que = [v[0]]
    while !que.empty?
        p = que.shift
        e[p].each do |q|
            if q != v[0] && par[q] == -1
                par[q] = p
                que << q
            end
        end
    end

    use = Array.new(n, false)
    v.each do |x|
        while x != -1 && !use[x]
            use[x] = true
            x = par[x]
        end
    end

    puts use.count(true)
end

main

Submission Info

Judge Result