Remove all adjacent duplicates in string

String Stack

72.8% acceptance

Feb 25, 2026

7061

275

You are given a string s consisting of lowercase English letters. A duplicate removal consists of choosing two adjacent and equal letters and removing them. We repeatedly make duplicate removals on s until we no longer can. Return the final string after all such duplicate removals have been made. It can be proven that the answer is unique.

Solution

Rust

Time O(n)

Space O(n)

LeetCode

solution.rs

impl Solution {
  pub fn remove_duplicates(s: String) -> String {
    let mut stack: Vec<char> = vec![];
    for c in s.chars() {
      if stack.last() == Some(&c) { stack.pop(); }
      else { stack.push(c); }
    }
    stack.into_iter().collect()
  }
}