結果

問題 No.834 Random Walk Trip
ユーザー te-sh
提出日時 2021-07-05 21:45:06
言語 Crystal
(1.14.0)
結果
AC  
実行時間 48 ms / 2,000 ms
コード長 4,753 bytes
コンパイル時間 13,870 ms
コンパイル使用メモリ 295,660 KB
実行使用メモリ 18,516 KB
最終ジャッジ日時 2024-07-01 12:02:21
合計ジャッジ時間 15,105 ms
ジャッジサーバーID
（参考情報） 		judge5 / judge2
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ファイルパターン 結果
other AC * 26
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ソースコード

diff #
プレゼンテーションモードにする

def main(io)
  n, m = io.get2
  io.put_e 1 if n == 1
  f = Fact(Mint).new(m)
  c = Mint.zero
  (0..m).each do |i|
    next unless (i % (n*2) == 0 || i % (n*2) == n*2-1) && (i+m) % 2 == 0
    x = (i+m) // 2
    c += f.combi(m, x)
  end
  (1..m).each do |i|
    next unless (i % (n*2) == 1 || i % (n*2) == 0) && (i+m) % 2 == 0
    x = (i+m) // 2
    c += f.combi(m, x)
  end
  io.put c
end
class Fact(T)
  def initialize(@n : Int32)
    @table = Array.new(@n+1, T.new(0))
    @table[0] = T.multiplicative_identity
    (1..@n).each do |i|
      @table[i] = @table[i-1] * i
    end
    @inv_table = Array.new(@n+1, T.new(0))
    @inv_table[@n] = T.multiplicative_identity // @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
macro min_u(a, b)
  {{a}} = Math.min({{a}}, {{b}})
end
macro max_u(a, b)
  {{a}} = Math.max({{a}}, {{b}})
end
def cdiv(a : Int, b : Int)
  (a + b - 1) // b
end
def isqrt(n : Int32)
  m = 46340
  r = (1..m).bsearch { |i| i**2 > n }
  r.nil? ? m : r - 1
end
def isqrt(n : Int64)
  m = 3037000499_i64
  r = (1_i64..m).bsearch { |i| i**2 > n }
  r.nil? ? m : r - 1
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
  def self.zero
    self.new(0)
  end
  def self.additive_identity
    self.new(0)
  end
  def self.multiplicative_identity
    self.new(1)
  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
struct Mint < ModInt; @@mod : Int32 = 10**9+7; end
class ProconIO
  def initialize
    @buf = [] of String
    @index = 0
  end
  def get(k : T.class = Int32) forall T
    get_v(k)
  end
  def get(*ks : T.class) forall T
    ks.map { |k| get_v(k) }
  end
  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
  def get_c(n : Int, *ks : T.class) forall T
    a = Array.new(n) { get(*ks) }
    ks.map_with_index { |_, i| a.map { |e| e[i] } }
  end
  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)
      print i < vs.size - 1 ? " " : "\n"
    end
  end
  def put_e(*vs)
    put(*vs)
    exit
  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 : String.class); get_token; end
  private def get_token
    if @buf.size == @index
      @buf = read_line.split
      @index = 0
    end
    v = @buf[@index]
    @index += 1
    v
  end
  private def put_v(vs : Enumerable)
    vs.each_with_index do |v, i|
      print v
      print " " if i < vs.size - 1
    end
  end
  private def put_v(v)
    print v
  end
end
main(ProconIO.new)
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