Array-2

game_of_life.py

@@ -0,0 +1,51 @@
+"""
+time - o(n)
+space - o(1)
+we follow the rules and change 0 to 1 and 1 to 0, however, this causes information
+loss. So we represent 0 -> 1 change as 2 and 1 -> 0 change as 3
+"""
+
+from typing import List
+
+
+class Solution:
+    def get_score(self, board, i, j):
+        direction = [
+            (0, -1),
+            (-1, -1),
+            (-1, 0),
+            (-1, 1),
+            (0, 1),
+            (1, 1),
+            (1, 0),
+            (1, -1),
+        ]
+        score = 0
+        for d in direction:
+            if 0 <= i + d[0] < len(board) and 0 <= j + d[1] < len(board[0]):
+                val = board[i + d[0]][j + d[1]]
+                if val < 2:
+                    score += val
+                elif val == 3:
+                    score += 1
+        return score
+
+    def gameOfLife(self, board: List[List[int]]) -> None:
+        """
+        Do not return anything, modify board in-place instead.
+        """
+        # 0 -> 1 = 2 and 1 -> 0 = 3
+        for i in range(len(board)):
+            for j in range(len(board[0])):
+                score = self.get_score(board, i, j)
+                if (score < 2 or score > 3) and board[i][j] == 1:
+                    board[i][j] = 3
+                elif score == 3 and board[i][j] == 0:
+                    board[i][j] = 2
+
+        for i in range(len(board)):
+            for j in range(len(board[0])):
+                if board[i][j] == 2:
+                    board[i][j] = 1
+                if board[i][j] == 3:
+                    board[i][j] = 0

missing_numbers.py

@@ -0,0 +1,19 @@
+"""
+time - o(n)
+space - o(1)
+we take each number in the array and head to the array[number] (using the number as an index)
+we make this number as negative, any number that is missing will have array[number] as positive
+"""
+
+from typing import List
+
+
+class Solution:
+    def findDisappearedNumbers(self, nums: List[int]) -> List[int]:
+        for i in range(len(nums)):
+            nums[abs(nums[i]) - 1] *= -1 if nums[abs(nums[i]) - 1] > 0 else 1
+        result = []
+        for i in range(len(nums)):
+            if nums[i] > 0:
+                result.append(i + 1)
+        return result