Earth - Lina

Gemfile.lock

@@ -0,0 +1,36 @@
+GEM
+  remote: https://rubygems.org/
+  specs:
+    ansi (1.5.0)
+    builder (3.2.4)
+    coderay (1.1.3)
+    method_source (1.0.0)
+    minitest (5.14.2)
+    minitest-reporters (1.4.2)
+      ansi
+      builder
+      minitest (>= 5.0)
+      ruby-progressbar
+    minitest-skip (0.0.3)
+      minitest (~> 5.0)
+    minitest-spec (0.0.2.1)
+      minitest (>= 3.0)
+    pry (0.13.1)
+      coderay (~> 1.1)
+      method_source (~> 1.0)
+    rake (13.0.1)
+    ruby-progressbar (1.10.1)
+
+PLATFORMS
+  ruby
+
+DEPENDENCIES
+  minitest
+  minitest-reporters
+  minitest-skip
+  minitest-spec
+  pry
+  rake
+
+BUNDLED WITH
+   2.1.4

lib/recursive-methods.rb

@@ -1,49 +1,136 @@
 # Authoring recursive algorithms. Add comments including time and space complexity for each method.
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def factorial(n)
-    raise NotImplementedError, "Method not implemented"
+
+    raise ArgumentError if n < 0
+
+    if n == 0 #base case
+        return 1
+    else
+        return n * factorial(n-1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
 def reverse(s)
-    raise NotImplementedError, "Method not implemented"
+    if s.length <= 1
+        return s
+    else
+        return s[-1] + reverse(s[1..-2]) + s[0]
+    end
 end
 
+# another way to do reverse
+# if s.length <= 1
+#     return s
+# else
+#     return reverse_inplace(s[1..-1]) + s[0]
+# end
+
+
+
 # Time complexity: ?
 # Space complexity: ?
-def reverse_inplace(s)
-    raise NotImplementedError, "Method not implemented"
+def reverse_inplace(s, low = 0, high = s.length - 1)
+    if low >= high
+        return s
+    else
+        temp = s[low]
+        s[low] = s[high]
+        s[high] = temp
+        return reverse_inplace(s, low + 1, high - 1)
+    end
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
+# Time complexity: O(n)
+# Space complexity: O(n)
 def bunny(n)
-    raise NotImplementedError, "Method not implemented"
+    if n == 0
+        return 0
+    else
+        return 2 + bunny(n-1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def nested(s)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
+def nested(s, low = 0, high = s.length - 1)
+    # if s.empty?
+    #     return true
+    # elsif s[0] == s[-1]
+    #     return false
+    # else
+    #     return nested(s[1..-2])
+    # end
+    #
+    if low > high
+        return true
+    elsif s[low] == s[high]
+        return false
+    else
+        nested(s, low + 1, high - 1)
+    end
+
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def search(array, value)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
+def search(array, value, index = 0)
+    # if array.empty?
+    #     return false
+    # elsif array[0] == value
+    #     return true
+    # else
+    #     return search(array[1..-1], value)
+    # end
+
+    if array.empty? || index > array.length - 1
+        return false
+    elsif array[index] == value
+        return true
+    else
+        search(array, value, index + 1)
+    end
 end
 
-# Time complexity: ?
-# Space complexity: ?
-def is_palindrome(s)
-    raise NotImplementedError, "Method not implemented"
+# Time complexity: O(n^2)
+# Space complexity: O(n^2)
+def is_palindrome(s, left = 0, right = s.length - 1)
+    # if s.length == 1 || s.empty?
+    #     return true
+    # end
+    #
+    # if s[0] == s[-1]
+    #     is_palindrome(s[1..-2])
+    # else
+    #     return false
+    # end
+    if left > right
+        return true
+    elsif s[left] != s[right]
+        return false
+    else
+        is_palindrome(s, left + 1, right - 1 )
+    end
+
 end
 
 # Time complexity: ?
 # Space complexity: ?
-def digit_match(n, m)
-    raise NotImplementedError, "Method not implemented"
+def digit_match(n, m, match_count = 0)
+
+    raise ArgumentError if n < 0 || n < 0
+
+    match_count += 1 if n % 10 == m % 10
+
+    if n < 10 || m < 10
+        return match_count
+    else
+        return digit_match(n/10, m/10, match_count)
+    end
+
 end

test/recursion_writing_test.rb

@@ -167,7 +167,7 @@
   end
 end
 
-xdescribe "nested" do
+describe "nested" do
   it "will return true for empystring" do
     # Arrange
     string = ""
@@ -213,7 +213,7 @@
   end
 end
 
-xdescribe "search" do
+describe "search" do
   it "will return false for empty array" do
     # Arrange
     item = "a"
@@ -263,7 +263,7 @@
     end      
 end
 
-xdescribe "is_palindrome" do
+describe "is_palindrome" do
   it "will return true for emptystring" do
     # Arrange
     string = ""
@@ -298,7 +298,7 @@
   end
 end
 
-xdescribe "digit_match" do
+describe "digit_match" do
   it "returns 4 for 1072503891 and 62530841" do
     # Arrange
     num1 = 1072503891