Refactored solutions 259 - 260

Solutions/259.py

@@ -1,36 +1,53 @@
 """
 Problem:
 
-Ghost is a two-person word game where players alternate appending letters to a word. The first person who spells out a word, or creates a prefix for which there is no possible continuation, loses. Here is a sample game:
+Ghost is a two-person word game where players alternate appending letters to a word.
+The first person who spells out a word, or creates a prefix for which there is no
+possible continuation, loses. Here is a sample game:
 
 Player 1: g
 Player 2: h
 Player 1: o
 Player 2: s
 Player 1: t [loses]
-Given a dictionary of words, determine the letters the first player should start with, such that with optimal play they cannot lose.
+Given a dictionary of words, determine the letters the first player should start with,
+such that with optimal play they cannot lose.
 
-For example, if the dictionary is ["cat", "calf", "dog", "bear"], the only winning start letter would be b.
+For example, if the dictionary is ["cat", "calf", "dog", "bear"], the only winning
+start letter would be b.
 """
 
 
-def get_winning_letters(words):
-    # creating a map of starting characters to the words
+from typing import List, Set
+
+
+def get_winning_letters(words: List[str]) -> Set[str]:
+    # requirements for winning start letter:
+    # - the length is even for all words starting with the character
     starting_char_freq = {}
     for word in words:
         if word[0] not in starting_char_freq:
             starting_char_freq[word[0]] = []
         starting_char_freq[word[0]].append(word)
-    # getting the winning start characters
-    # requirements: only 1 word starts with the character & its length is even
+
     winning_start_letters = set()
     for starting_char in starting_char_freq:
-        if len(starting_char_freq[starting_char]) == 1:
-            if len(starting_char_freq[starting_char][0]) % 2 == 0:
-                winning_start_letters.add(starting_char)
+        for word in starting_char_freq[starting_char]:
+            if len(word) % 2 != 0:
+                break
+        else:
+            winning_start_letters.add(starting_char)
     return winning_start_letters
 
 
-# DRIVER CODE
-print(get_winning_letters(["cat", "calf", "dog", "bear"]))
-print(get_winning_letters(["cat", "something", "hi", "calf", "dog", "bear"]))
+if __name__ == "__main__":
+    print(get_winning_letters(["cat", "calf", "dog", "bear"]))
+    print(get_winning_letters(["something", "hi", "cat", "dog", "bear", "hola"]))
+
+
+"""
+SPECS:
+
+TIME COMPLEXITY: O(n)
+SPACE COMPLEXITY: O(n)
+"""

Solutions/260.py

@@ -1,18 +1,22 @@
 """
 Problem:
 
-The sequence [0, 1, ..., N] has been jumbled, and the only clue you have for its order is an array representing whether each number is larger or smaller than the last. Given this information, reconstruct an array that is consistent with it. For example, given [None, +, +, -, +], you could return [1, 2, 3, 0, 4].
+The sequence [0, 1, ..., N] has been jumbled, and the only clue you have for its order
+is an array representing whether each number is larger or smaller than the last. Given
+this information, reconstruct an array that is consistent with it. For example, given
+[None, +, +, -, +], you could return [1, 2, 3, 0, 4].
 """
 
 
-def get_sequence(relative_arr):
-    # getting the number of '+' and generating the first number
+from typing import List, Optional
+
+
+def get_sequence(relative_arr: List[Optional[str]]) -> List[int]:
     length = len(relative_arr)
     larger_count = relative_arr.count("+")
     first_num = length - 1 - larger_count
     larger_num, smaller_num = first_num + 1, first_num - 1
 
-    # generating the result array
     result = [first_num]
     for elem in relative_arr[1:]:
         if elem == "+":
@@ -24,5 +28,13 @@ def get_sequence(relative_arr):
     return result
 
 
-# DRIVER CODE
-print(get_sequence([None, "+", "+", "-", "+"]))
+if __name__ == "__main__":
+    print(get_sequence([None, "+", "+", "-", "+"]))
+
+
+"""
+SPECS:
+
+TIME COMPLEXITY: O(n)
+SPACE COMPLEXITY: O(n)
+"""