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

Input: s = "abcd", k = 2
Output: "abcd"
Explanation: There's nothing to delete.

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"

pair를 사용해서 몇개가 누적되는지 계속 파악해나간다. 개수와 같아지면 pop을해서 빼 버리고,

마지막에 살아있으면서 누적되어 있는 애들은 count수 만큼 더해주면 된다.

class Solution {
public:
	string removeDuplicates(string s, int k) {
		stack<pair<char, int>> sStack;
		for (int i = 0; i < s.size(); ++i)
		{
			if (sStack.empty())
				sStack.push(make_pair(s[i], 1));
			else
			{
				if (s[i] == sStack.top().first)
				{
					sStack.top().second++;
					if (sStack.top().second == k)
						sStack.pop();
				}
				else
				{
					sStack.push(make_pair(s[i], 1));
				}
			}
		}
		string result;
		while (!sStack.empty())
		{
			int count = sStack.top().second;
			for (int i = 0; i < count; ++i)
			{
				result += sStack.top().first;
			}
			sStack.pop();
		}
		std::reverse(result.begin(), result.end());
		return result;
	}
};

Runtime: 20 ms, faster than 49.40% of C++ online submissions for Remove All Adjacent Duplicates in String II.

Memory Usage: 8.1 MB, less than 76.46% of C++ online submissions for Remove All Adjacent Duplicates in String II.

45~ 75까지 나온다.