Smallest KLength Subsequence With Occurrences of a Letter.py

class Solution:
    def smallestSubsequence(self, s: str, k: int, letter: str, repetition: int) -> str:
        s = list(s)
        stack = []
        countAll = s.count(letter)
        count = 0
        for ind, i in enumerate(s):
            while stack and stack[-1] > i:
                if stack[-1] == letter and i != letter:
                    if countAll+count-1 < repetition:
                        break
                if len(stack)+len(s)-ind-1 < k:
                    break
                if stack[-1] == letter:
                    count-=1
                stack.pop()
            stack.append(i)
            if i == letter:
                count+=1
                countAll-=1
        temp = 0
        while len(stack)+temp > k:
            if stack[-1] == letter and count <= repetition:
                temp+=1
            if stack[-1] == letter:
                count-=1
            stack.pop()
        return "".join(stack)+temp*letter