Leetcode 316 - Remove Duplicate Letters (python)

Counter를 알게된 순간...

collections 에 어떤게 있는지 알아보는 계기가 되었다.

class Solution:
    def removeDuplicateLetters(self, s: str) -> str:

        counter, result, stack = collections.Counter(s), set(), []

        for c in s:
            counter[c] -= 1
            if c in result:
                continue

            while stack and c < stack[-1] and counter[stack[-1]] > 0:
                result.remove(stack.pop())

            stack.append(c)
            result.add(c)

        return ''.join(stack)

https://leetcode.com/problems/remove-duplicate-letters/

Remove Duplicate Letters - LeetCode