public class Solution
extends Object
1209 - Remove All Adjacent Duplicates in String II\.
Medium
You are given a string `s` and an integer `k`, a `k` **duplicate removal** consists of choosing `k` adjacent and equal letters from `s` and removing them, causing the left and the right side of the deleted substring to concatenate together.
We repeatedly make `k` **duplicate removals** on `s` until we no longer can.
Return the final string after all such duplicate removals have been made. It is guaranteed that the answer is unique.
**Example 1:**
**Input:** s = "abcd", k = 2
**Output:** "abcd"
**Explanation:** There's nothing to delete.
**Example 2:**
**Input:** s = "deeedbbcccbdaa", k = 3
**Output:** "aa"
**Explanation:**
First delete "eee" and "ccc", get "ddbbbdaa"
Then delete "bbb", get "dddaa"
Finally delete "ddd", get "aa"
**Example 3:**
**Input:** s = "pbbcggttciiippooaais", k = 2
**Output:** "ps"
**Constraints:**
* 1 <= s.length <= 105
* 2 <= k <= 104
* `s` only contains lower case English letters.