Abigail C - Rock

hash_practice/exercises.py

@@ -2,18 +2,46 @@
 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: ?
+        Time Complexity: O(n * m log(m))  (m is the max length of the word) 
+        Space Complexity: O(n)
     """
-    pass
+    string_dict = {}
+    # see if the sorted value is a key in the dict and if not add the element in the dict we are on as an array.
+    for unsorted_word in strings:
+        sorted_word = str(sorted(unsorted_word))
+        if sorted_word in string_dict:
+            string_dict[sorted_word].append(unsorted_word)
+        else:
+            string_dict[sorted_word] = [unsorted_word]
+    return list(string_dict.values())
+    # If the sorted value is in the dict add the element we are on to the key's value with the existing array.
+
 
 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: ?
     """
-    pass
+        # Create an empty dict
+    num_dict = {}
+    # Iterate through nums and add count as the value of the dictionary.
+    for num in nums:
+        if num in num_dict:
+            num_dict[num] += 1
+        else:
+            num_dict[num] = 1
+    # Once we have the dict full we will find the values with the largest keys k times.
+    sorted_list = set(sorted(num_dict.values(), reverse=True)[:k])
+
+    result = []
+    for key, value in num_dict.items():
+        if len(result) == k:
+            return result
+        if value in sorted_list:
+            result.append(key)
+    return result
+    # return the keys in a list
 
 
 def valid_sudoku(table):
@@ -25,5 +53,26 @@ def valid_sudoku(table):
         Time Complexity: ?
         Space Complexity: ?
     """
-    pass
+    rows_dict = {}
+    col_dict = {}
+
+    for i in range(9):
+        col_dict[i] = {}
+    for row_index in range(len(table)):
+        rows_dict[row_index] = {}
+        row = table[row_index]
+        for index in range(len(row)):
+            if row[index] == ".":
+                continue
+            else:
+                if row[index] in rows_dict[row_index]:
+                    return False
+                else:
+                    rows_dict[row_index][row[index]] = index
+
+                if row[index] in col_dict[row_index]:
+                    return False
+                else:
+                    col_dict[row_index][row[index]] = index
+    return True