1209.spec.ts

/*
https://leetcode.com/problems/remove-all-adjacent-duplicates-in-string-ii/

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.
*/

function removeDuplicates(s: string, k: number): string {

    if (k > s.length)
        return s;

    let res: string = '';
    const stack: [string, number][] = [];
    for (const letter of s) {
        if (stack.length && stack[stack.length - 1][0] == letter)
            stack[stack.length - 1][1] += 1;
        else
            stack.push([letter, 1]);

        if (stack.length && stack[stack.length - 1][1] === k)
            stack.pop();
    }

    for (const pair of stack) {
        res += pair[0].repeat(pair[1]);
    }
    return res
}