Grokking Data Structures & Algorithms for Coding Interviews
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Problem 7: Remove All Adjacent Duplicates In String (medium)
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Problem Statement

Give a string s, convert it into a valid string. A string is considered valid if it does not have any two adjacent duplicate characters.

To make a string valid, we will perform a duplicate removal process. 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.

Examples

Example 1

  • Input: "abbaca"
  • Expected Output: "ca"
  • Description: We remove 'b' from "abbaca" to get "aaca", then remove 'a' from "aaca" to get "ca"

Example 2

  • Input: "azxxzy"
  • Expected Output: "ay"
  • Description: We remove 'x' from "azxxzy" to get "azzy", then remove 'z' from "azzy" to get "ay"

Example 3

  • Input: "abba"
  • Expected Output: ""
  • Description: We remove 'b' from "abba" to get "aa", then remove 'a' from "aa" to get an empty string

Constraints:

  • 1 <= str.length <= 10<sup>5</sup>
  • str consists of lowercase English letters.

Try it yourself

Try solving this question here:

Python3
Python3
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