diff --git a/lib/exercises.rb b/lib/exercises.rb index e1b3850..c039486 100644 --- a/lib/exercises.rb +++ b/lib/exercises.rb @@ -1,19 +1,48 @@ # This method will return an array of arrays. # Each subarray will have strings which are anagrams of each other -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n) +# Space Complexity: O(n) def grouped_anagrams(strings) - raise NotImplementedError, "Method hasn't been implemented yet!" + return [] if strings.empty? + return [strings] if strings.length == 1 + + hash = {} + + strings.each do |str| + char = str.split("").sort.join("") + if hash[char].nil? + hash[char] = [str] + else + hash[char] << str + end + end + return hash.values end # This method will return the k most common elements # in the case of a tie it will select the first occuring element. -# Time Complexity: ? -# Space Complexity: ? +# Time Complexity: O(n log n) +# Space Complexity: O(n) def top_k_frequent_elements(list, k) - raise NotImplementedError, "Method hasn't been implemented yet!" + return [] if list.length == 0 + + hash = {} + + list.each do |element| + if hash[element] + hash[element] += 1 + else + hash[element] = 1 + end + end + sorted = hash.sort_by {|key, value| -value } + result = [] + k.times do |index| + result << sorted[index].first + end + return result end