Create 1227.AirplaneSeatAssignmentProbability.py

Medium/1227.AirplaneSeatAssignmentProbability.py

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+'''
+    n passengers board an airplane with exactly n seats. The 
+    first passenger has lost the ticket and picks a seat 
+    randomly. But after that, the rest of passengers will:
+        - Take their own seat if it is still available, 
+        - Pick other seats randomly when they find their 
+          seat occupied 
+
+    What is the probability that the n-th person can get his 
+    own seat?
+
+    Example:
+    Input: n = 1
+    Output: 1.00000
+    Explanation: The first person can only get the first seat.
+
+    Example:
+    Input: n = 2
+    Output: 0.50000
+    Explanation: The second person has a probability of 0.5 
+                 to get the second seat (when first person 
+                 gets the first seat).
+
+    Constraints:
+        - 1 <= n <= 10^5
+'''
+#Difficulty: Medium
+#100 / 100 test cases passed.
+#Runtime: 32 ms
+#Memory Usage: 14.2 MB
+
+#Runtime: 32 ms, faster than 49.09% of Python3 online submissions for Airplane Seat Assignment Probability.
+#Memory Usage: 14.2 MB, less than 23.33% of Python3 online submissions for Airplane Seat Assignment Probability.
+
+class Solution:
+    def nthPersonGetsNthSeat(self, n: int) -> float:
+        return 0.5 if n > 1 else 1