From edecefaea2a255ef522f05179aa542fb478f2688 Mon Sep 17 00:00:00 2001
From: Lola Llanes <mslourdesllanes@gmail.com>
Date: Tue, 5 Jan 2021 00:04:45 -0800
Subject: [PATCH] completed grouped_anagrams and top_k_frequent_elements

---
 lib/exercises.rb | 58 +++++++++++++++++++++++++++++++++++++++++++-----
 1 file changed, 52 insertions(+), 6 deletions(-)

diff --git a/lib/exercises.rb b/lib/exercises.rb
index e1b3850..dbffdfd 100644
--- a/lib/exercises.rb
+++ b/lib/exercises.rb
@@ -1,19 +1,65 @@
 
 # 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(m * n) 
+# Space Complexity: O(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  anagram_hash = {}
+
+  strings.each do |word|
+    letters = word.chars.sort
+    sorted_letters = letters.join
+
+    if !anagram_hash.has_key?(sorted_letters)
+      anagram_hash[sorted_letters] = [word]
+    else anagram_hash[sorted_letters] << word
+    end
+  end
+
+  return anagram_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(m * n)
+# Space Complexity: O(n)
+# https://stackoverflow.com/questions/4264133/descending-sort-by-value-of-a-hash-in-ruby
+# https://courses.cs.washington.edu/courses/cse373/18au/files/slides/lecture13.pdf
+
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  if list.empty? 
+    return list 
+  end
+
+  element_frequency = {}
+  
+  list.each do |num|
+    if element_frequency[num]
+      element_frequency[num] += 1
+    else
+      element_frequency[num] = 1
+    end
+  end
+
+  frequent_elements = []
+
+  k.times do
+    max_frequency = 0
+    max_frequent_elements = nil
+
+    element_frequency.each do |key, value|
+      if value > max_frequency
+        max_frequent_elements = key
+        max_frequency = value
+      end
+    end
+
+    frequent_elements << max_frequent_elements
+    element_frequency[max_frequent_elements] = 0
+  end
+
+  return frequent_elements
 end