Minimum Number of Chairs in a Waiting Room

Description

You are given a string s. Simulate events at each second i:

- If s[i] == 'E', a person enters the waiting room and takes one of the chairs in it.

- If s[i] == 'L', a person leaves the waiting room, freeing up a chair.

Return the minimum number of chairs needed so that a chair is available for every person who enters the waiting room given that it is initially empty.