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#3168
Easy Algorithms

Minimum number of chairs in a waiting room

String Simulation
79.2% acceptance
Feb 24, 2026
155
14
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.

Solution

Rust
Time O(n)
Space O(1)
LeetCode
solution.rs 
impl Solution {
  pub fn minimum_chairs(s: String) -> i32 {
    let mut count = 0i32;
    let mut max_count = 0i32;
    for &b in s.as_bytes() {
      if b == b'E' {
        count += 1;
        max_count = max_count.max(count);
      } else {
        count -= 1;
      }
    }
    max_count
  }
}