diff --git a/Gemfile.lock b/Gemfile.lock new file mode 100644 index 0000000..630ea95 --- /dev/null +++ b/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 diff --git a/lib/recursive-methods.rb b/lib/recursive-methods.rb index fbf6faa..a4c55da 100644 --- a/lib/recursive-methods.rb +++ b/lib/recursive-methods.rb @@ -1,49 +1,112 @@ # Authoring recursive algorithms. Add comments including time and space complexity for each method. -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n), where n is the length +# Space complexity: O(n), uses up some space in the call stack until it reaches the base case def factorial(n) - raise NotImplementedError, "Method not implemented" + if n == 0 + return 1 + elsif n <= 0 + raise ArgumentError + 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 + end + + return s[-1] + reverse(s[1..-2]) + s[0] end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n) +# Space complexity: O(n) def reverse_inplace(s) - raise NotImplementedError, "Method not implemented" + first = 0 + last = s.length - 1 + return reverse_inplace_helper(s, first, last) +end + +def reverse_inplace_helper(s, first = 0, last = s.length - 1) + if first > last + return s + end + + temp = s[first] + s[first] = s[last] + s[last] = temp + + return reverse_inplace_helper(s, first + 1, last - 1) 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 + end + + return 2 + bunny(n-1) end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n^2) +# Space complexity: O(n^2) def nested(s) - raise NotImplementedError, "Method not implemented" + if s.length < 1 + return true + elsif s == "(" || s == ")" + return false + elsif s[0] == "(" && s[-1] == ")" + return nested(s[1..-2]) + else + return false + end + end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n^2) +# Space complexity: O(n^2) def search(array, value) - raise NotImplementedError, "Method not implemented" + if array.empty? + return false + elsif value == array[0] + return true + else + return search(array[1..-1], value) + end end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n^2) +# Space complexity: O(n^2) def is_palindrome(s) - raise NotImplementedError, "Method not implemented" + if s.length < 1 + return true + elsif s[0] != s[-1] + return false + else + return is_palindrome(s[1..-2]) + end end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n^2)? +# Space complexity: O(n^2)? def digit_match(n, m) - raise NotImplementedError, "Method not implemented" + n = n.to_s + m = m.to_s + + count = 0 + return digit_match_counter(n, m, count) +end + +def digit_match_counter(n, m, count) + if n.length == 0 || m.length == 0 + return count + elsif n[-1] == m[-1] + count += 1 + end + + return digit_match_counter(n[0..-2], m[0..-2], count) end \ No newline at end of file diff --git a/test/recursion_writing_test.rb b/test/recursion_writing_test.rb index 3b30725..4984dad 100644 --- a/test/recursion_writing_test.rb +++ b/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