Minimum Number of Chairs in a Waiting Room

Ah, the classic dilemma of waiting rooms! You know the scene: you walk into a doctor’s office, and it looks like a game of musical chairs, but with no music and a lot more anxiety. The problem at hand is to determine the minimum number of chairs required in a waiting room based on the flow of people entering and exiting.

Imagine this: you’re sitting there, nervously tapping your foot, while the receptionist is juggling appointments like a circus performer. Suddenly, someone enters (an ‘E’) and you think, “Great, another person to share my anxiety with!” But then, just as quickly, someone else leaves (an ‘L’), and you’re left wondering if you should have brought a book.

In this problem, we need to calculate the maximum number of chairs needed at any point in time based on a string of events where ‘E’ represents someone entering and ‘L’ represents someone leaving.

Code Solution

Copy Code

class Solution:
    def minimumChairs(self, s: str) -> int:
        ans = 0
        chairs = 0

        for c in s:
            chairs += 1 if c == 'E' else -1
            ans = max(ans, chairs)

        return ans

Approach Explanation

The code works by iterating through the string of events. For each character:

• If it’s an ‘E’, we increase the chair count (someone enters).
• If it’s an ‘L’, we decrease the chair count (someone leaves).
• We keep track of the maximum number of chairs needed at any point in time using the ans variable.

Time and Space Complexity

Complexity Type	Complexity
Time Complexity	O(n), where n is the length of the string. We traverse the string once.
Space Complexity	O(1), as we are using a constant amount of space for our variables.

Real-World Example

Picture this: you’re at a coffee shop, and it’s packed. People are coming in and out like it’s a revolving door. You notice that at one point, there are 10 people inside, and only 5 chairs. The barista is sweating bullets trying to keep up with the orders. This scenario mirrors our problem perfectly! The maximum number of chairs needed at any time is the answer we seek.

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