Here are the questions from Telephonic interview round:

1. Given a string of digits and a number k. Return minimum number after removing k digits from the given string.

For example:
Input: s ="3542219" and k=3
Output: 2219

Input: s="1119" and k=3
Output: 1

2. Set matrix zeroes without using extra spaces: https://leetcode.com/problems/set-matrix-zeroes/