結果

問題 No.758 VVVVV
ユーザー te-shte-sh
提出日時 2021-07-12 16:12:23
言語 Crystal
(1.11.2)
結果
AC  
実行時間 90 ms / 2,000 ms
コード長 9,397 bytes
コンパイル時間 20,583 ms
コンパイル使用メモリ 262,568 KB
実行使用メモリ 20,432 KB
最終ジャッジ日時 2023-09-14 20:36:46
合計ジャッジ時間 22,792 ms
ジャッジサーバーID
（参考情報） 		judge14 / judge12
このコードへのチャレンジ
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テストケース

テストケース表示
入力 結果 実行時間
実行使用メモリ
testcase_00 AC 2 ms
4,380 KB
testcase_01 AC 3 ms
4,380 KB
testcase_02 AC 2 ms
4,380 KB
testcase_03 AC 80 ms
19,376 KB
testcase_04 AC 32 ms
11,944 KB
testcase_05 AC 23 ms
9,412 KB
testcase_06 AC 21 ms
9,244 KB
testcase_07 AC 76 ms
19,868 KB
testcase_08 AC 37 ms
12,368 KB
testcase_09 AC 13 ms
7,744 KB
testcase_10 AC 25 ms
9,716 KB
testcase_11 AC 77 ms
19,984 KB
testcase_12 AC 18 ms
8,276 KB
testcase_13 AC 23 ms
9,276 KB
testcase_14 AC 13 ms
7,320 KB
testcase_15 AC 10 ms
6,352 KB
testcase_16 AC 11 ms
7,000 KB
testcase_17 AC 64 ms
17,940 KB
testcase_18 AC 32 ms
11,964 KB
testcase_19 AC 78 ms
19,780 KB
testcase_20 AC 20 ms
9,068 KB
testcase_21 AC 22 ms
9,292 KB
testcase_22 AC 90 ms
20,432 KB
testcase_23 AC 2 ms
4,380 KB
testcase_24 AC 3 ms
4,448 KB
testcase_25 AC 3 ms
4,376 KB
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ソースコード

diff # 

def solve(io)
  n = io.get

  io.put_e 1 if n == 1

  g = Graph.new(n)
  (n-1).times do
    a, b = io.get2; a -= 1; b -= 1
    g.add_edge_b(a, b)
  end
  t = g.tree(0)

  x = (0...n).count { |u| t.children_of(u).empty? }
  f = Fact(Mint).new(n-1)
  io.put f.combi(n-1, x-1) * f.combi(n-2, x-1) // x
end

struct Int
  def cdiv(b : Int)
    (self + b - 1) // b
  end

  def bit?(i : Int)
    bit(i) == 1
  end

  def set_bit(i : Int)
    self | (self.class.new(1) << i)
  end

  def reset_bit(i : Int)
    self & ~(self.class.new(1) << i)
  end

  {% if compare_versions(env("CRYSTAL_VERSION") || "0.0.0", "0.34.0") < 0 %}
    def bit_length : Int32
      x = self < 0 ? ~self : self

      if x.is_a?(Int::Primitive)
        Int32.new(sizeof(self) * 8 - x.leading_zeros_count)
      else
        to_s(2).size
      end
    end
  {% end %}
end

struct Int32
  SQRT_MAX = 46_340_i32

  def isqrt
    m = SQRT_MAX
    r = (1_i32..SQRT_MAX).bsearch { |i| i**2 > self }
    r.nil? ? SQRT_MAX : r - 1
  end
end

struct Int64
  SQRT_MAX = 3_037_000_499_i64

  def isqrt
    r = (1_i64..SQRT_MAX).bsearch { |i| i**2 > self }
    r.nil? ? SQRT_MAX : r - 1
  end
end

struct Number
  {% if compare_versions(env("CRYSTAL_VERSION") || "0.0.0", "1.1.0") < 0 %}
    def zero?
      self == 0
    end

    def positive?
      self > 0
    end

    def negative?
      self < 0
    end
  {% end %}

  {% if compare_versions(env("CRYSTAL_VERSION") || "0.0.0", "0.36.0") < 0 %}
    def self.additive_identity
      zero
    end

    def self.multiplicative_identity
      new(1)
    end
  {% end %}
end

class Array
  macro new_md(*args, &block)
    {% if !block %}
      {% for arg, i in args[0...-2] %}
        Array.new({{arg}}) {
      {% end %}
      Array.new({{args[-2]}}, {{args[-1]}})
      {% for arg in args[0...-2] %}
        }
      {% end %}
    {% else %}
      {% for arg, i in args %}
        Array.new({{arg}}) { |_i{{i}}|
      {% end %}
      {% for block_arg, i in block.args %}
        {{block_arg}} = _i{{i}}
      {% end %}
      {{block.body}}
      {% for arg in args %}
        }
      {% end %}
    {% end %}
  end
end

class ProconIO
  def initialize(@ins : IO = STDIN, @outs : IO = STDOUT)
    @buf = [] of String
    @index = 0
  end

  def get(k : T.class = Int32) forall T
    get_v(k)
  end

  macro define_get
    {% for i in (2..9) %}
      def get(
            {% for j in (1..i) %}
              k{{j}}{% if j < i %},{% end %}
            {% end %}
          )
        {
          {% for j in (1..i) %}
            get(k{{j}}){% if j < i %},{% end %}
          {% end %}
        }
      end
    {% end %}
  end
  define_get

  macro define_getn
    {% for i in (2..9) %}
      def get{{i}}(k : T.class = Int32) forall T
        get(
          {% for j in (1..i) %}
            k{% if j < i %}, {% end %}
          {% end %}
        )
      end
    {% end %}
  end
  define_getn

  def get_a(n : Int, k : T.class = Int32) forall T
    Array.new(n) { get_v(k) }
  end

  def get_c(n : Int, k : T.class = Int32) forall T
    get_a(n, k)
  end

  macro define_get_c
    {% for i in (2..9) %}
      def get_c(
            n : Int,
            {% for j in (1..i) %}
              k{{j}}{% if j < i %},{% end %}
            {% end %}
          )
        a = Array.new(n) do
          get(
            {% for j in (1..i) %}
              k{{j}}{% if j < i %},{% end %}
            {% end %}
          )
        end
        {
          {% for j in (1..i) %}
            a.map { |e| e[{{j-1}}] }{% if j < i %},{% end %}
          {% end %}
        }
      end
    {% end %}
  end
  define_get_c

  macro define_getn_c
    {% for i in (2..9) %}
      def get{{i}}_c(n : Int, k : T.class = Int32) forall T
        get_c(
          n,
          {% for j in (1..i) %}
            k{% if j < i %}, {% end %}
          {% end %}
        )
      end
    {% end %}
  end
  define_getn_c

  def get_m(r : Int, c : Int, k : T.class = Int32) forall T
    Array.new(r) { get_a(c, k) }
  end

  def put(*vs)
    vs.each.with_index do |v, i|
      put_v(v)
      @outs.print i < vs.size - 1 ? " " : "\n"
    end
  end

  def put_e(*vs)
    put(*vs)
    exit
  end

  def put_f(*vs)
    put(*vs)
    @outs.flush
  end


  private def get_v(k : Int32.class); get_token.to_i32; end
  private def get_v(k : Int64.class); get_token.to_i64; end
  private def get_v(k : UInt32.class); get_token.to_u32; end
  private def get_v(k : UInt64.class); get_token.to_u64; end
  private def get_v(k : Float64.class); get_token.to_f64; end
  private def get_v(k : String.class); get_token; end

  private def get_token
    if @buf.size == @index
      str = @ins.read_line
      @buf = str.split
      @index = 0
    end
    v = @buf[@index]
    @index += 1
    v
  end

  private def put_v(vs : Enumerable)
    vs.each_with_index do |v, i|
      @outs.print v
      @outs.print " " if i < vs.size - 1
    end
  end

  private def put_v(v)
    @outs.print v
  end
end

macro min_u(a, b)
  {{a}} = Math.min({{a}}, {{b}})
end

macro max_u(a, b)
  {{a}} = Math.max({{a}}, {{b}})
end

macro zip(a, *b, &block)
  {{a}}.zip({{*b}}) {{block}}
end

class Fact(T)
  def initialize(@n : Int32)
    @table = Array.new(@n+1, T.multiplicative_identity)
    (1..@n).each do |i|
      @table[i] = @table[i-1] * i
    end

    @inv_table = Array.new(@n+1, T.multiplicative_identity)
    @inv_table[@n] //= @table[@n]
    (1..@n).reverse_each do |i|
      @inv_table[i-1] = @inv_table[i] * i
    end
  end

  getter table : Array(T)

  getter inv_table : Array(T)

  def fact(n : Int)
    @table[n]
  end

  def perm(n : Int, r : Int)
    @table[n] * @inv_table[n-r]
  end

  def combi(n : Int, r : Int)
    @table[n] * @inv_table[r] * @inv_table[n-r]
  end

  def homo(n : Int, r : Int)
    combi(n+r-1, r)
  end


  @table : Array(T)
  @inv_table : Array(T)
end

def powr(a : T, n : Int, i : T = T.multiplicative_identity) forall T
  powr(a, n, i) { |a, b| a * b }
end

def powr(a : T, n : Int, i : T = T.multiplicative_identity, &block) forall T
  return i if n == 0
  r, b = i, a
  while n > 0
    r = yield r, b if n.bit(0) == 1
    b = yield b, b
    n >>= 1
  end
  r
end

def ext_gcd(a : T, b : T) forall T
  if a == 0
    {b, T.new(0), T.new(1)}
  else
    g, x, y = ext_gcd(b%a, a)
    {g, y-(b//a)*x, x}
  end
end

abstract struct ModInt < Number
  macro new_type(name, mod)
    struct {{name}} < ModInt
      @@mod : Int32 = {{mod}}
    end
  end

  def initialize(v : Int)
    @v = (v % @@mod).to_i64
  end

  def_hash @@mod, @v

  def to_s
    @v.to_s
  end

  def to_s(io : IO) : Nil
    @v.to_s(io)
  end

  getter v : Int64

  delegate to_i, to: @v

  def ==(r : self)
    @v == r.v
  end

  def ==(r : Int)
    @v == (r % @@mod)
  end

  def - : self
    m(-@v)
  end

  def +(r : self)
    m(@v + r.v)
  end

  def +(r : Int)
    self + m(r)
  end

  def -(r : self)
    m(@v - r.v)
  end

  def -(r : Int)
    self - m(r)
  end

  def *(r : self)
    m(@v * r.v)
  end

  def *(r : Int)
    self * m(r)
  end

  def //(r : self)
    self * r.inv
  end

  def //(r : Int)
    self // m(r)
  end

  def **(n : Int)
    powr(self, n)
  end

  def inv
    m(ext_gcd(@v.to_i32, @@mod)[1])
  end


  private def m(v : Int)
    self.class.new(v)
  end
end
ModInt.new_type(Mint, 10**9+7)

require "bit_array"

class Graph
  alias Node = Int32

  def initialize(@size : Node)
    @g = Array(Array(Node)).new(@size) { [] of Node }
  end

  getter size : Int32

  delegate :[], to: @g

  def add_edge(u : Node, v : Node)
    @g[u] << v
  end

  def add_edge_b(u : Node, v : Node)
    @g[u] << v
    @g[v] << u
  end

  def bfs(u : Node)
    b = BitArray.new(@size)
    yield u, -1
    b[u] = true
    q = Deque.new([u])
    until q.empty?
      v = q.shift
      @g[v].each do |w|
        next if b[w]
        yield w, v
        b[w] = true
        q.push(w)
      end
    end
  end
end

class GraphW(T)
  alias Node = Int32

  struct Edge(T)
    def initialize(@src : Node, @dst : Node, @wt : T)
    end

    getter src : Node, dst : Node

    getter wt : T
  end
      
  def initialize(@size : Node, @inf = 10**9)
    @g = Array(Array(Edge(T))).new(@size) { [] of Edge(T) }
  end

  getter size : Int32

  getter inf : T

  delegate :[], to: @g

  def add_edge(u : Node, v : Node, wt : T)
    @g[u] << Edge.new(u, v, wt)
  end

  def add_edge_b(u : Node, v : Node, wt : T)
    @g[u] << Edge.new(u, v, wt)
    @g[v] << Edge.new(v, u, wt)
  end
end

class Tree
  alias Node = Graph::Node

  def initialize(@g : Graph, @root : Node)
    size = @g.size
    @parent = Array.new(size, 0)
    @depth = Array.new(size, -1)
    @dfs_order = [] of Node

    s = [{@root, @root}]
    until s.empty?
      u, p = s.pop

      @parent[u] = p
      @depth[u] = @depth[p] + 1
      @dfs_order << u

      @g[u].each do |v|
        s.push({v, u}) if v != p
      end
    end

    @size = Array.new(size, 1)
    @dfs_order.reverse_each do |u|
      @size[@parent[u]] += @size[u] if u != @root
    end
  end

  getter root : Node

  getter dfs_order : Array(Node)

  def parent_of(u : Node)
    @parent[u]
  end

  def depth_of(u : Node)
    @depth[u]
  end

  def size_of(u : Node)
    @size[u]
  end

  def children_of(u : Node)
    @g[u].reject { |v| v == @parent[u] }
  end


  @parent : Array(Node)
  @depth : Array(Int32)
  @size : Array(Int32)
end

class Graph
  def tree(root)
    Tree.new(self, root)
  end
end

solve(ProconIO.new)
0