diff --git a/lib/max_subarray.rb b/lib/max_subarray.rb index 5204edb..f78242d 100644 --- a/lib/max_subarray.rb +++ b/lib/max_subarray.rb @@ -1,8 +1,31 @@ -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n) +# Space Complexity: O(1) def max_sub_array(nums) - return 0 if nums == nil - - raise NotImplementedError, "Method not implemented yet!" + max_so_far = nums[0] + max_ending_here = nums[0] + i = 1 + while i < nums.length + max_ending_here = max_ending_here + nums[i] + if max_so_far < max_ending_here + max_so_far = max_ending_here + end + if max_ending_here < 0 + max_ending_here = 0 + end + i += 1 + end + return max_so_far end + +# Initialize: +# max_so_far = 0 +# max_ending_here = 0 + +# Loop for each element of the array +# (a) max_ending_here = max_ending_here + a[i] +# (b) if(max_ending_here < 0) +# max_ending_here = 0 +# (c) if(max_so_far < max_ending_here) +# max_so_far = max_ending_here +# return max_so_far \ No newline at end of file diff --git a/lib/newman_conway.rb b/lib/newman_conway.rb index 4c985cd..38bbdde 100644 --- a/lib/newman_conway.rb +++ b/lib/newman_conway.rb @@ -1,7 +1,22 @@ - - -# Time complexity: ? -# Space Complexity: ? +# Time complexity: O(n) +# Space Complexity: O(n) def newman_conway(num) - raise NotImplementedError, "newman_conway isn't implemented" -end \ No newline at end of file + raise ArgumentError if num < 1 + sequence = [] + n = 1 + while n <= num + sequence.push(get_newman_num(n)) + n += 1 + end + return sequence.join(" ") +end + +def get_newman_num(num) + if num < 3 + return 1 + else + num = get_newman_num(get_newman_num(num - 1)) + get_newman_num(num - get_newman_num(num - 1)) + # P(n) = P(P(n - 1)) + P(n - P(n - 1)) + return num + end +end diff --git a/test/max_sub_array_test.rb b/test/max_sub_array_test.rb index 3253cdf..e27e1ca 100644 --- a/test/max_sub_array_test.rb +++ b/test/max_sub_array_test.rb @@ -1,6 +1,6 @@ require_relative "test_helper" -xdescribe "max subarray" do +describe "max subarray" do it "will work for [-2,1,-3,4,-1,2,1,-5,4]" do # Arrange input = [-2,1,-3,4,-1,2,1,-5,4]