diff --git a/lib/recursive-methods.rb b/lib/recursive-methods.rb index fbf6faa..e54d8c4 100644 --- a/lib/recursive-methods.rb +++ b/lib/recursive-methods.rb @@ -3,47 +3,81 @@ # Time complexity: ? # Space complexity: ? def factorial(n) - raise NotImplementedError, "Method not implemented" + if n == 0 + return 1 + elsif n == -1 + raise ArgumentError, "cannot calculate for a negative number" + else + return n * factorial(n - 1) + end end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n), where n is equal to the number passed +# Space complexity: O(n), where n is equal to the number passed + def reverse(s) - raise NotImplementedError, "Method not implemented" + if s.length <= 1 + return s + else + return s[-1] + reverse(s[0..-2]) + end end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n), n is the number of characters in the string +# Space complexity: O(n), n is the number of characters in the string + def reverse_inplace(s) - raise NotImplementedError, "Method not implemented" + #will need a helper method + if s == "" + return s + end + + temp = s[0] + s[0] = s[s.length - 1] + s[s.length - 1] = temp + + if s.length > 1 + s[1..-2] = reverse_inplace(s[1..-2]) + end + return s end # Time complexity: ? # Space complexity: ? 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: ? +# Time complexity: O(n) where n is the number of bunnies +# Space complexity: O(n) where n is the number of bunnies def nested(s) - raise NotImplementedError, "Method not implemented" + if s == "" || s == "()" + return true + elsif s[0] == "(" && s[-1] == ")" && nested(s[1..-2]) + return true + else + return false + end end -# Time complexity: ? -# Space complexity: ? +# Time complexity: O(n) where n is the length of the string +# Space complexity: O(n) where n is the length of the string def search(array, value) - raise NotImplementedError, "Method not implemented" + raise NotImplementedError, "Method not implemented" end # Time complexity: ? # Space complexity: ? def is_palindrome(s) - raise NotImplementedError, "Method not implemented" + raise NotImplementedError, "Method not implemented" end # Time complexity: ? # Space complexity: ? def digit_match(n, m) - raise NotImplementedError, "Method not implemented" -end \ No newline at end of file + raise NotImplementedError, "Method not implemented" +end diff --git a/specs/recursion_writing_spec.rb b/specs/recursion_writing_spec.rb index d8fb1ed..2b04432 100644 --- a/specs/recursion_writing_spec.rb +++ b/specs/recursion_writing_spec.rb @@ -1,7 +1,7 @@ -require 'minitest/autorun' -require 'minitest/reporters' +require "minitest/autorun" +require "minitest/reporters" require "minitest/skip_dsl" -require_relative '../lib/recursive-methods' +require_relative "../lib/recursive-methods" describe "factorial" do it "will find the factorial of 0" do @@ -23,8 +23,7 @@ answer = factorial(num) # Assert - expect(answer).must_equal 5*4*3*2*1 - + expect(answer).must_equal 5 * 4 * 3 * 2 * 1 end it "will raise an ArgumentError if given a number not >= 0" do @@ -38,7 +37,7 @@ end end -xdescribe "reverse" do +describe "reverse" do it "will reverse 'cat'" do # Arrange string = "cat" @@ -83,8 +82,7 @@ end end - -xdescribe "reverse_in_place" do +describe "reverse_in_place" do it "will reverse 'cat'" do # Arrange string = "cat" @@ -129,7 +127,7 @@ end end -xdescribe "bunny" do +describe "bunny" do it "returns 0 for 0 bunnies" do # Arrange count = 0 @@ -164,7 +162,7 @@ end end -xdescribe "nested" do +describe "nested" do it "will return true for empystring" do # Arrange string = "" @@ -224,40 +222,40 @@ end it "will return true when looking for something in the array" do - # Arrange - item = "a" - array = ["b", "c", "a"] + # Arrange + item = "a" + array = ["b", "c", "a"] - # Act - answer = search(array, item) + # Act + answer = search(array, item) - # Assert - expect(answer).must_equal true + # Assert + expect(answer).must_equal true end it "will return false when looking for something not in the array" do # Arrange item = "x" array = ["b", "c", "a"] - + # Act answer = search(array, item) - + # Assert expect(answer).must_equal false - end - - it "will return true when finding something at the front of the array" do - # Arrange - item = "b" - array = ["b", "c", "a"] - - # Act - answer = search(array, item) - - # Assert - expect(answer).must_equal true - end + end + + it "will return true when finding something at the front of the array" do + # Arrange + item = "b" + array = ["b", "c", "a"] + + # Act + answer = search(array, item) + + # Assert + expect(answer).must_equal true + end end xdescribe "is_palindrome" do @@ -304,8 +302,8 @@ # Act answer = digit_match(num1, num2) - # Assert - expect(answer).must_equal 4 + # Assert + expect(answer).must_equal 4 end it "returns 0 for nonmatching numbers" do @@ -316,8 +314,8 @@ # Act answer = digit_match(num1, num2) - # Assert - expect(answer).must_equal 0 + # Assert + expect(answer).must_equal 0 end it "returns 3 for 841 and 62530841" do @@ -328,7 +326,7 @@ # Act answer = digit_match(num1, num2) - # Assert - expect(answer).must_equal 3 + # Assert + expect(answer).must_equal 3 end -end \ No newline at end of file +end