Watch 10 video solutions for Minimum Number of Chairs in a Waiting Room, a easy level problem involving String, Simulation. This walkthrough by NeetCode has 174,333 views views. Want to try solving it yourself? Practice on FleetCode or read the detailed text solution.
You are given a string s. Simulate events at each second i:
s[i] == 'E', a person enters the waiting room and takes one of the chairs in it.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.
Example 1:
Input: s = "EEEEEEE"
Output: 7
Explanation:
After each second, a person enters the waiting room and no person leaves it. Therefore, a minimum of 7 chairs is needed.
Example 2:
Input: s = "ELELEEL"
Output: 2
Explanation:
Let's consider that there are 2 chairs in the waiting room. The table below shows the state of the waiting room at each second.
| Second | Event | People in the Waiting Room | Available Chairs |
|---|---|---|---|
| 0 | Enter | 1 | 1 |
| 1 | Leave | 0 | 2 |
| 2 | Enter | 1 | 1 |
| 3 | Leave | 0 | 2 |
| 4 | Enter | 1 | 1 |
| 5 | Enter | 2 | 0 |
| 6 | Leave | 1 | 1 |
Example 3:
Input: s = "ELEELEELLL"
Output: 3
Explanation:
Let's consider that there are 3 chairs in the waiting room. The table below shows the state of the waiting room at each second.
| Second | Event | People in the Waiting Room | Available Chairs |
|---|---|---|---|
| 0 | Enter | 1 | 2 |
| 1 | Leave | 0 | 3 |
| 2 | Enter | 1 | 2 |
| 3 | Enter | 2 | 1 |
| 4 | Leave | 1 | 2 |
| 5 | Enter | 2 | 1 |
| 6 | Enter | 3 | 0 |
| 7 | Leave | 2 | 1 |
| 8 | Leave | 1 | 2 |
| 9 | Leave | 0 | 3 |
Constraints:
1 <= s.length <= 50s consists only of the letters 'E' and 'L'.s represents a valid sequence of entries and exits.