Remove All Adjacent Duplicates in String in C++

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"

**Constraints:**
1 <= s.length <= 105
2 <= k <= 104
s only contains lower case English letters.