human
I found an interesting problem on https://leetcode.com/problems/remove-k-digits/:
Given a non-negative integer num represented as a string, remove k digits from the number so that the new number is the smallest possible.

Note:

The length of num is less than 10002 and will be ≥ k.
The given num does not contain any leading zero.



Example 1:

Input: num = "1432219", k = 3
Output: "1219"
Explanation: Remove the three digits 4, 3, and 2 to form the new number 1219 which is the smallest.


Example 2:

Input: num = "10200", k = 1
Output: "200"
Explanation: Remove the leading 1 and the number is 200. Note that the output must not contain leading zeroes.


Example 3:

Input: num = "10", k = 2
Output: "0"
Explanation: Remove all the digits from the number and it is left with nothing which is 0.

I tried it in Python, but could not do it. Can you solve it?

 ... What is a the Python program you requested?
assistant
#Here is the Python program you requested.

class Solution:
     def removeKdigits(self, num, k):
         """
         :type num: str
         :type k: int
         :rtype: str
         """
         while True:
             if k == 0:
                 return num if num != "" else "0"
             if num == "":
                 return "0"
             index = 0
             num_len = len(num)
             while True:
                 if index == num_len - 1:
                     num = num[:-1]
                     k -= 1
                     break
                 if num[index] > num[index + 1]:
                     new_num = num[:index] + num[index+1:]
                     num = new_num.lstrip("0")
                     k -= 1
                     break
                 index += 1