Building a tree of moves for a knight in chess

.rspec

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+--color
+--require spec_helper
+--format documentation

Gemfile

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+source "https://rubygems.org"
+
+gem 'rspec'
+gem 'guard-rspec', require: false

Gemfile.lock

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+GEM
+  remote: https://rubygems.org/
+  specs:
+    coderay (1.1.1)
+    diff-lcs (1.3)
+    ffi (1.9.17)
+    formatador (0.2.5)
+    guard (2.14.1)
+      formatador (>= 0.2.4)
+      listen (>= 2.7, < 4.0)
+      lumberjack (~> 1.0)
+      nenv (~> 0.1)
+      notiffany (~> 0.0)
+      pry (>= 0.9.12)
+      shellany (~> 0.0)
+      thor (>= 0.18.1)
+    guard-compat (1.2.1)
+    guard-rspec (4.7.3)
+      guard (~> 2.1)
+      guard-compat (~> 1.1)
+      rspec (>= 2.99.0, < 4.0)
+    listen (3.1.5)
+      rb-fsevent (~> 0.9, >= 0.9.4)
+      rb-inotify (~> 0.9, >= 0.9.7)
+      ruby_dep (~> 1.2)
+    lumberjack (1.0.11)
+    method_source (0.8.2)
+    nenv (0.3.0)
+    notiffany (0.1.1)
+      nenv (~> 0.1)
+      shellany (~> 0.0)
+    pry (0.10.4)
+      coderay (~> 1.1.0)
+      method_source (~> 0.8.1)
+      slop (~> 3.4)
+    rb-fsevent (0.9.8)
+    rb-inotify (0.9.8)
+      ffi (>= 0.5.0)
+    rspec (3.5.0)
+      rspec-core (~> 3.5.0)
+      rspec-expectations (~> 3.5.0)
+      rspec-mocks (~> 3.5.0)
+    rspec-core (3.5.4)
+      rspec-support (~> 3.5.0)
+    rspec-expectations (3.5.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.5.0)
+    rspec-mocks (3.5.0)
+      diff-lcs (>= 1.2.0, < 2.0)
+      rspec-support (~> 3.5.0)
+    rspec-support (3.5.0)
+    ruby_dep (1.5.0)
+    shellany (0.0.1)
+    slop (3.6.0)
+    thor (0.19.4)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  guard-rspec
+  rspec
+
+BUNDLED WITH
+   1.14.3

Guardfile

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+# A sample Guardfile
+# More info at https://github.com/guard/guard#readme
+
+## Uncomment and set this to only include directories you want to watch
+# directories %w(app lib config test spec features) \
+#  .select{|d| Dir.exists?(d) ? d : UI.warning("Directory #{d} does not exist")}
+
+## Note: if you are using the `directories` clause above and you are not
+## watching the project directory ('.'), then you will want to move
+## the Guardfile to a watched dir and symlink it back, e.g.
+#
+#  $ mkdir config
+#  $ mv Guardfile config/
+#  $ ln -s config/Guardfile .
+#
+# and, you'll have to watch "config/Guardfile" instead of "Guardfile"
+
+# Note: The cmd option is now required due to the increasing number of ways
+#       rspec may be run, below are examples of the most common uses.
+#  * bundler: 'bundle exec rspec'
+#  * bundler binstubs: 'bin/rspec'
+#  * spring: 'bin/rspec' (This will use spring if running and you have
+#                          installed the spring binstubs per the docs)
+#  * zeus: 'zeus rspec' (requires the server to be started separately)
+#  * 'just' rspec: 'rspec'
+
+guard :rspec, cmd: "bundle exec rspec" do
+  require "guard/rspec/dsl"
+  dsl = Guard::RSpec::Dsl.new(self)
+
+  # Feel free to open issues for suggestions and improvements
+
+  # RSpec files
+  rspec = dsl.rspec
+  watch(rspec.spec_helper) { rspec.spec_dir }
+  watch(rspec.spec_support) { rspec.spec_dir }
+  watch(rspec.spec_files)
+
+  # Ruby files
+  ruby = dsl.ruby
+  dsl.watch_spec_files_for(ruby.lib_files)
+
+  # Rails files
+  rails = dsl.rails(view_extensions: %w(erb haml slim))
+  dsl.watch_spec_files_for(rails.app_files)
+  dsl.watch_spec_files_for(rails.views)
+
+  watch(rails.controllers) do |m|
+    [
+      rspec.spec.call("routing/#{m[1]}_routing"),
+      rspec.spec.call("controllers/#{m[1]}_controller"),
+      rspec.spec.call("acceptance/#{m[1]}")
+    ]
+  end
+
+  # Rails config changes
+  watch(rails.spec_helper)     { rspec.spec_dir }
+  watch(rails.routes)          { "#{rspec.spec_dir}/routing" }
+  watch(rails.app_controller)  { "#{rspec.spec_dir}/controllers" }
+
+  # Capybara features specs
+  watch(rails.view_dirs)     { |m| rspec.spec.call("features/#{m[1]}") }
+  watch(rails.layouts)       { |m| rspec.spec.call("features/#{m[1]}") }
+
+  # Turnip features and steps
+  watch(%r{^spec/acceptance/(.+)\.feature$})
+  watch(%r{^spec/acceptance/steps/(.+)_steps\.rb$}) do |m|
+    Dir[File.join("**/#{m[1]}.feature")][0] || "spec/acceptance"
+  end
+end

README.md

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 # assignment_search
-Marco?  Polo!
+Andrea A
 
 [A data structures and algorithms Ruby challenge from the Viking Code School](http://www.vikingcodeschool.com)
+
+# Running the code 
+```
+load 'knight_searcher.rb'
+load 'benchmark.rb'
+
+tree = MoveTree.new([2,2],1)
+searcher = KnightSearcher.new( tree )
+bm = BenchmarkTest.new(searcher)
+```
+
+
+# What data structure is used to implement DFS?
+Stack
+
+# What data structure is typically used to implement BFS?
+Queue
+
+# Which one can be done recursively? (the clue should be the data structure)
+DFS is best designed to be done recursively
+
+
+# Which one would you use to print a list of all the nodes in a tree or graph, starting with depth 1, then depth 2, then depth 3 etc.?
+BFS prints all the nodes at each level before going to the next level
+
+
+
+# What is the difference between a tree and a graph?
+Trees have nodes an graphs have vertices.
+There is no root node in a graph, so they are slightly less structured than trees.
+A tree has a hierarchical structure but a graph doesn't.
+
+### Pseudocode
+** 1) Searching a simple tree of nodes where each Node has an array of child nodes (some_node.children) using DFS. **
+
+```Store the node to be found
+Initialize an empty stack
+
+  starting at root, searching for x
+   current_node = root
+   loop - while stack is not empty
+   Take the end of the stack - y
+     if current_node.children is equal to x 
+         return x  and break loop
+         else current_node = current_node.children - push on to stack
+     break the loop if current_node has no children
+   end the loop
+ ```
+
+** 2) Searching the same tree using BFS. **
+
+```Store the node to be found
+Initialize an empty queue
+
+  Put all nodes on the queue
+
+ starting at root, searching for x
+   current_node = root
+   loop - while queue is not empty
+    Take the top of the queue - y
+   if current_node.children is equal to x 
+         return x  and break loop
+         else current_node = current_node.children - push on to queue
+   ```
+
+
+** 3. Searching a graph (represented however you feel most comfortable -- Edge List, Adjacency List or Adjacency Matrix) using DFS. **
+
+Searching the same tree using BFS.
+
+Store the node to be found
+
+``` starting at root
+   current_node = root and mark this as visited
+    get the next node from the root and iterate through its nodes
+      if the node hasn't been visited call the function again
+      else go the the next level up
+      break when there is no children
+```
+
+** 4. Searching the same graph using BFS. **
+
+Store the node to be found
+
+``` starting at root
+   current_node = root and mark this as visited
+    put the root on the queue
+    loop while the queue still elements
+      take an item from the top of the queue
+      check if the item is equal to the node to be found
+      iterate through the dequeued node 
+      if the node is not visited put it on the queue otherwise go to the next.
+```

lib/benchmarking.rb

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+
+require_relative 'move_tree'
+require_relative 'knight_searcher'
+
+class Benchmarking
+
+  attr_accessor :bfs_time, :dfs_time, :knight_searcher
+
+  def initialize
+     tree = MoveTree.new([1,2],1)
+     @knight_searcher = KnightSearcher.new( tree )
+     @bfs_time = 0
+     @dfs_time = 0
+  end
+
+  def bfs_measure(coords)
+    start_time = Time.now
+    10.times do
+      @knight_searcher.bfs_for(coords)
+    end
+    @bfs_time = (Time.now - start_time) / 60
+  end
+
+  def dfs_measure(coords)
+    start_time = Time.now
+    10.times do
+      @knight_searcher.dfs_for(coords)
+    end
+    @dfs_time  = (Time.now - start_time) / 60
+  end
+
+  def statistics
+    puts "Breadth-first search vs Depth-first search"
+    puts "The bfs searcher took #{@bfs_time} and the dfs searcher took #{@dfs_time}"
+  end
+
+end
+

lib/knight_searcher.rb

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+
+require_relative 'move_tree'
+
+class KnightSearcher
+
+  attr_accessor :knight_tree, :moves, :trail
+
+  def initialize(tree)
+    @knight_tree = tree.root
+    @trail = Array.new
+  end
+
+
+  def bfs_for(target_coords)
+    queue = []
+    @moves = 0
+    @trail = []
+    queue << @knight_tree
+
+    while queue.length != 0
+      current = queue.shift
+      @moves += 1
+      @trail << [current.x, current.y]
+      if(current.x == target_coords[0] && current.y == target_coords[1])
+
+        print_trail
+        return "Found node"
+      elsif(current.children) 
+        current.children.each do | descendants|
+          queue << descendants
+        end
+      end
+    end
+    puts "Path not found"
+  end
+
+   def dfs_for(target_coords)
+    stack = []
+    @moves = 0
+    @trail = []
+    stack << @knight_tree
+
+    while stack.length != 0
+      current = stack.pop
+      @moves += 1
+      @trail << [current.x, current.y]
+      if(current.x == target_coords[0] && current.y == target_coords[1])
+        print_trail
+        return "Found node"
+      elsif(current.children) 
+        current.children.each do | descendants|
+          stack << descendants
+        end
+      end
+    end
+    puts "Path not found"
+  end
+
+# Output the sequence of moves used to get there as well as the final depth required.
+  def print_trail
+    puts "#{@moves} moves:"
+    @trail.each do |x|
+      puts "[#{x[0]}, #{x[1]}]"
+    end
+  end
+end
+