经典排序算法资料及 ruby 实现

经典排序算法资料及ruby实现

学习<算法导论>时到网络上找了一批排序算法的资料. 结合参考资料分别用ruby写了一遍. 这里分享给大家. 配上图与参考资料.

插入排序

  def insert_sort!    (0...self.length).to_a.each do |j|      key = self[j]      i = j - 1;      while i >= 0 and self[i] > key        self[i+1] = self[i]        i = i-1      end      self[i+1] = key    end    self  end

冒泡排序

wikipedia 详解: http://en.wikipedia.org/wiki/Insertion_sort

Problem Solving: Searching and sorting

  def bubble_sort!    f = 1    while f < self.length      (0...(self.length-f)).to_a.each do |i|        self[i], self[i+1] = self[i+1], self[i] if self[i] > self[i+1]      end      f += 1    end    self  end

鸡尾酒排序

wikipedia 详解: http://en.wikipedia.org/wiki/Cocktail_sort

def cocktail_sort!    f  = 0    while f < self.length/2      i = 0      while i < self.length - 1        self[i], self[i+1] = self[i+1], self[i] if self[i] > self[i+1]        i += 1;      end      t = self.length - 1      while t > 0         self[t], self[t-1] = self[t-1], self[t] if self[t] < self[t-1]         t -= 1      end       f += 1    end    self  end

合并排序

wikipedia 详解: http://en.wikipedia.org/wiki/Merge_sort

  def merge_sort!    return self if self.size <= 1    left = self[0, self.size/2]    right = self[self.size/2, self.size - self.size/2]    Array.merge(left.merge_sort, right.merge_sort)  end  def self.merge(left, right)    sorted = []    until left.empty? or right.empty?        sorted << (left.first <= right.first ? left.shift : right.shift)    end    sorted + left + right  end

快速排序

wikipedia详解: http://en.wikipedia.org/wiki/Quicksort

三种qicksort的实现方式: http://c2.com/cgi/wiki?QuickSortInRuby

在线图示加语音详解: http://www.csanimated.com/animation.php?t=Quicksort

  def quick_sort!    return [] if self.empty?    x, *a = self    left, right = a.partition{|t| t < x}    left.quick_sort + [x] + right.quick_sort  end

heapSort

wikipedia 详解: http://en.wikipedia.org/wiki/Heapsort

更深入分析: http://www.personal.kent.edu/~rmuhamma/Algorithms/MyAlgorithms/Sorting/heapSort.htm

  def heap_sort!    # in pseudo-code, heapify only called once, so inline it here    ((length - 2) / 2).downto(0) {|start| siftdown(start, length - 1)}    # "end" is a ruby keyword    (length - 1).downto(1) do |end_|      self[end_], self[0] = self[0], self[end_]      siftdown(0, end_ - 1)    end    self  end  def siftdown(start, end_)    root = start    loop do      child = root * 2 + 1      break if child > end_      if child + 1 <= end_ and self[child] < self[child + 1]        child += 1      end      if self[root] < self[child]        self[root], self[child] = self[child], self[root]        root = child      else        break      end    end  end

最后, 附上完整的ruby实现:

class Array  # 插入排序  def insert_sort!    (0...self.length).to_a.each do |j|      key = self[j]      i = j - 1;      while i >= 0 and self[i] > key        self[i+1] = self[i]        i = i-1      end      self[i+1] = key    end    self  end  # 快速排序  def quick_sort!    return [] if self.empty?    x, *a = self    left, right = a.partition{|t| t < x}    left.quick_sort + [x] + right.quick_sort  end  # 冒泡排序  def bubble_sort!    f = 1    while f < self.length      (0...(self.length-f)).to_a.each do |i|        self[i], self[i+1] = self[i+1], self[i] if self[i] > self[i+1]      end      f += 1    end    self  end  # 鸡尾酒排序(>_<)  def cocktail_sort!    f  = 0    while f < self.length/2      i = 0      while i < self.length - 1        self[i], self[i+1] = self[i+1], self[i] if self[i] > self[i+1]        i += 1;      end      t = self.length - 1      while t > 0         self[t], self[t-1] = self[t-1], self[t] if self[t] < self[t-1]         t -= 1      end       f += 1    end    self  end  # 合并排序  def merge_sort!    return self if self.size <= 1    left = self[0, self.size/2]    right = self[self.size/2, self.size - self.size/2]    Array.merge(left.merge_sort, right.merge_sort)  end  def self.merge(left, right)    sorted = []    until left.empty? or right.empty?        sorted << (left.first <= right.first ? left.shift : right.shift)    end    sorted + left + right  end  # heap排序  def heap_sort!    # in pseudo-code, heapify only called once, so inline it here    ((length - 2) / 2).downto(0) {|start| siftdown(start, length - 1)}    # "end" is a ruby keyword    (length - 1).downto(1) do |end_|      self[end_], self[0] = self[0], self[end_]      siftdown(0, end_ - 1)    end    self  end  def siftdown(start, end_)    root = start    loop do      child = root * 2 + 1      break if child > end_      if child + 1 <= end_ and self[child] < self[child + 1]        child += 1      end      if self[root] < self[child]        self[root], self[child] = self[child], self[root]        root = child      else        break      end    end  end  %w(insert quick bubble cocktail merge heap).each do |metd|    define_method("#{metd}_sort") do      self.dup.send("#{metd.to_s}_sort!")     end  endendp b = ((1..100).to_a + (20..80).to_a).shuffle.sample(19)p b.methods.grep /_sort/p b.insert_sortp b.bubble_sortp b.quick_sortp b.cocktail_sortp b.merge_sortp b.heap_sort

转自：https://ruby-china.org/topics/20569