LC-0402 Medium LeetCode

402. Remove K Digits

Read the full problem statement on LeetCode.

Difficulty: medium Acceptance: 35% Topics: String, Stack, Greedy, Monotonic Stack

Reading material

Strings 12 min Stacks & Queues 11 min Greedy 11 min

Reference solution (spoiler · python)

# Time:  O(n)
# Space: O(n)

class Solution(object):
    def removeKdigits(self, num, k):
        """
        :type num: str
        :type k: int
        :rtype: str
        """
        result = []
        for d in num:
            while k and result and result[-1] > d:
                result.pop()
                k -= 1
            result.append(d)
        return ''.join(result).lstrip('0')[:-k or None] or '0'

Solution from kamyu104/LeetCode-Solutions · MIT