Given a string s of lowercase letters, repeatedly delete any two adjacent equal letters until no such pair remains. Return the final string (it is the same no matter which pair you delete first).
Examples
Input: s = "abbaca"
Output: "ca"
Explanation: "abbaca" -> "aaca" -> "ca".
Input: s = "azxxzy"
Output: "ay"
Constraints
0 <= len(s) <= 10**5- Target:
O(n)time
Goals
- Use the top of a stack to detect an adjacent duplicate
- See why one left-to-right pass handles chained removals