Update 24_game.py

Author: erjan

24_game.py

@@ -111,3 +111,42 @@ def fn(*args):
             return False 
 
         return fn(*cards)
+    
+-----------------------------------------------------------------------------------------------------
+class Solution:
+    # All possible operations we can perform on two numbers.
+    def generate_possible_results(self, a: float, b: float) -> List[float]:
+        res = [a + b, a - b, b - a, a * b]
+        if a:
+            res.append(b / a)
+        if b:
+            res.append(a / b)  
+        return res
+    
+    # Check if using current list we can react result 24.
+    def check_if_result_reached(self, cards: List[float]) -> bool:
+        # Base Case: We have only one number left, check if it is approximately 24.
+        if len(cards) == 1:
+            return abs(cards[0] - 24.0) <= 0.1
+
+        for i in range(len(cards)):
+            for j in range(i + 1, len(cards)):
+                # Create a new list with the remaining numbers and the new result.
+                new_list = [number for k, number in enumerate(cards) if (k != i and k != j)]
+                
+                # For any two numbers in our list, we perform every operation one by one.
+                for res in self.generate_possible_results(cards[i], cards[j]):
+                    # Add the new result to the list.
+                    new_list.append(res)
+                    
+                    # Check if using this new list we can obtain the result 24.
+                    if self.check_if_result_reached(new_list):
+                        return True
+                    
+                    # Backtrack: remove the result from the list.
+                    new_list.pop()
+                    
+        return False
+    
+    def judgePoint24(self, cards: List[int]) -> bool:
+        return self.check_if_result_reached(cards)