Scissors - Araceli

hash_practice/exercises.py

@@ -2,18 +2,53 @@
 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)
+        Space Complexity: O(n)
     """
-    pass
+
+    result = {}
+
+    for i in strings:
+        x = "".join(sorted(i))
+        if x in result:
+            result[x].append(i)
+        else:
+            result[x] = [i]
+
+    return list(result.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
+
+    number_frequency = {}
+    frequency_list = {}
+
+    for i in nums:
+        if i not in number_frequency:
+            number_frequency[i] = 1
+        else:
+            number_frequency[i] += 1
+
+    for key,value in number_frequency.items():
+
+        if value not in frequency_list:
+            frequency_list[value] = [key]
+        else:
+            frequency_list[value].append(key)
+
+    result = []
+
+    for i in range(len(nums),0,-1):
+        if i in frequency_list:
+            result.extend(frequency_list[i])
+        if len(result) >= k:
+            break
+
+    return result
 
 
 def valid_sudoku(table):
@@ -22,8 +57,28 @@ def valid_sudoku(table):
         Each element can either be a ".", or a digit 1-9
         The same digit cannot appear twice or more in the same 
         row, column or 3x3 subgrid
-        Time Complexity: ?
-        Space Complexity: ?
+        Time Complexity: O(n)
+        Space Complexity: O(n)
     """
-    pass
+
+    for i in range(9):
+        row = {}
+        column = {}
+        block = {}
+        row_cube = 3 * (i//3)
+        column_cube = 3 * (i%3)
+        for j in range(9):
+            if table[i][j]!='.' and table[i][j] in row:
+                return False
+            row[table[i][j]] = 1
+            if table[j][i]!='.' and table[j][i] in column:
+                return False
+            column[table[j][i]] = 1
+            rc= row_cube+j//3
+            cc = column_cube + j%3
+            if table[rc][cc] in block and table[rc][cc]!='.':
+                return False
+            block[table[rc][cc]]=1
+
+    return True