【综合】天梯算法

# encoding = UTF-8

class Student
  
  attr_accessor :name
  attr_accessor :rating
  attr_accessor :rank
  attr_accessor :_solve
  attr_accessor :_drating
  
  def initialize(name = "Unknown", rak = 100, rtg = 1500, solve = 0)
    @rank = rak.to_i
    @name = name
    @rating = rtg.to_i
    @_drating = 0
    @_solve = solve.to_i
  end
  
  def initialize(str2)
    str = str2.to_s
    data = str.split(‘ ‘)
    @rank = data[0].to_i
    @name = data[1]
    @rating = data[2].to_i
    @_solve = data[3].to_i
    @_drating = 0
  end
  
    def update(d) # 累加 rating 改变量
    @_drating += d
    end
    
  def modify # 更新rating
    @rating += @_drating
    @_drating = 0
        @rating = @rating.to_i
  end
  
    def toStringLine
        return "#{@rank}\t#{@name}\t#{@rating}\n"
    end
    
  def print
    #puts "#{@rank}\t#{@name}\t#{@rating}"
        puts "#{@rating}"
  end
  
end

$Kcef = 60 # 比赛的系数

=begin
Rating算法：
针对两个参加比赛的人，互相比较，每次比较都更新一次_drating。

比较法则：
先比较题数：多者胜，少者负；
若平手，比较排名；
根据比较结果选取系数进行计算。

更新系数法则：
将本场的比赛系数按参赛人数分配给各个学生
计算方法如下：
  cef = $Kcef / sz

更新法则：
更新时，将两两同学互相比较，然后每次计算出的增量累加到_drating上即可
增量计算方法如下：
  A: dA = cef * (sA - eA)
  B: dB = cef * (sB - eB)
最后直接累加即可。
=end

def calc_eA_eB(rA, rB)
    da = (rB - rA) / 400.0
  db = -da
  ta = 10.0**da + 1.0
  tb = 10.0**db + 1.0
  ea = 1.0 / ta
  eb = 1.0 / tb
  return [ea, eb]
end

def calc_sA_sB(a, b)
  solveA = a._solve
  solveB = b._solve
  pA = a.rank
  pB = b.rank
  if solveA < solveB
    return [0.0, 1.0]
  elsif solveA > solveB
    return [1.0, 0.0]
  elsif pA < pB
    return [1.0, 0.0]
  else
    return [0.0, 1.0]
  end
end

def calc_cef(ra, rb, sz)
    return $Kcef / sz
end

def competition(a, b, sz) # 修改两人的增量
    eA, eB = calc_eA_eB(a.rating.to_f, b.rating.to_f)
  sA, sB = calc_sA_sB(a, b)
    cef = calc_cef(a.rank.to_f, b.rank.to_f, sz.to_f)
  dA = (sA - eA) * cef
    dB = (sB - eB) * cef
    a.update(dA)
    b.update(dB)
end

def read( path )
    items = Array.new
    File.open(path, :encoding => ‘utf-8‘).each_line do |line|
        item = Student.new(line)
        items << item
    end
    sz = items.size
    # 逐一比较
    for i in 0...sz
        for j in 0...sz
            if i == j then
              next
            else 
              competition(items[i], items[j], sz.to_i);
            end 
        end
    end
    # 自身比较
    items.each do |data|
        temp = data
        temp.modify # 更新这场的rating
        competition(temp, data, sz)
        temp.modify # 自我比较后的rating
        data.modify # 对 rating 取平均值
        data.rating = ((temp.rating.to_i + data.rating.to_i ) / 2).to_i
    end
    
    file = File.new("result.txt", "w+")
    items.each do |data|
        data.modify
        file.print data.toStringLine
    end
end
read("contest1.txt")