From df987d59ca8c751c3d25d0bfa9ef81f3c05b4186 Mon Sep 17 00:00:00 2001
From: Sharon Cheung <keikei1128@g.ucla.edu>
Date: Mon, 14 Sep 2020 22:00:26 -0700
Subject: [PATCH] tests passed

---
 lib/exercises.rb | 43 ++++++++++++++++++++++++++++++++++++-------
 1 file changed, 36 insertions(+), 7 deletions(-)

diff --git a/lib/exercises.rb b/lib/exercises.rb
index e1b3850..2cde640 100644
--- a/lib/exercises.rb
+++ b/lib/exercises.rb
@@ -1,21 +1,50 @@
 
 # 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(n2)
+# Space Complexity: O(n)
 
 def grouped_anagrams(strings)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
+  return [] if strings.length == 0
+  result =  {}
+  strings.each do |word|
+    char = word.chars.sort.join
+    result[char] ||= []
+    result[char] << word
+  end
+  return result.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)
+# Space Complexity: O(n)
 def top_k_frequent_elements(list, k)
-  raise NotImplementedError, "Method hasn't been implemented yet!"
-end
+  return [] if list.length == 0
+  frequency = {}
+  # number as key 
+  # frequency as value
+
+  list.each do |num|
+    if frequency[num].nil?
+      frequency[num] = 1
+    else
+      frequency[num] += 1
+    end
+  end
 
+  result = []
+  
+  frequency.keys.each do |num|
+    if result.length < k
+      result << num
+    else
+      return result
+    end
+  end
+
+  return result
+end
 
 # This method will return the true if the table is still
 #   a valid sudoku table.