Scissors - Hena

hash_practice/exercises.py

@@ -2,18 +2,57 @@
 def grouped_anagrams(strings):
     """ This method will return an array of arrays.
         Each subarray will have strings which are anagrams of each other
-        Time Complexity: ?
-        Space Complexity: ?
-    """
-    pass
+        Time Complexity: O(n)
+        Space Complexity: O(n)
+"""
+    hash_table = {}
+    for word in strings:
+        # sort each char of word into a list
+        sorted_word = sorted(word)
+        # join the sorted chars back into a word
+        anagram = ''.join(sorted_word)
+        if anagram in hash_table:
+            # if anagram is already a key in hash table,
+            # append the current word to the value
+            hash_table[anagram].append(word)  
+        else:
+            # else, assign anagram as a key in the hash table
+            # and the current word as its value in list form
+            hash_table[anagram] = [word]
+    print(hash_table)     
+    # return just the list of all the values
+    return list(hash_table.values())
 
 def top_k_frequent_elements(nums, k):
     """ 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)
     """
-    pass
+    if not nums:
+        return nums
+
+    hash_table = {}
+    for num in nums:
+        if num in hash_table:
+            hash_table[num] += 1
+        else:
+            hash_table[num] = 1
+
+    print(hash_table.items())
+
+    # didn't grasp 100%, so listed out steps
+    # grab key-value pairs in hash_table
+    # let key be the second value in tuple
+    # reverse sort tuples by value into list
+    sorted_by_value = sorted(hash_table.items(), key = lambda tuple: tuple[1], reverse=True)                                      
+    print(sorted_by_value)
+    result = []
+    # for first k nums in reversed list of tuples
+    # append the value, or first value of tuple to result list
+    for i in range(k):                             
+        result.append(sorted_by_value[i][0])
+    return result
 
 
 def valid_sudoku(table):
@@ -24,6 +63,8 @@ def valid_sudoku(table):
         row, column or 3x3 subgrid
         Time Complexity: ?
         Space Complexity: ?
+
+        2powerful4me
     """
     pass