I recently gave a phone screen for Meta's Machine Learning Engineer position and have been advanced to the On-Site. To give back to the community that has greatly aided my preparation,

1. https://leetcode.com/problems/minimum-remove-to-make-valid-parentheses/
2. Given two arrays representing bus ticket prices for departures and returns, respectively, where the index corresponds to the timestamp (in days) and the value represents the price, the task is to find the minimum cost of purchasing a valid pair of tickets. The return ticket must be for a date on or after the corresponding departure's day.

For instance, consider the arrays departure = [10, 3, 10, 9, 3] and return = [4, 20, 6, 7, 10]. The minimum cost for a valid pair is 3 + 6 = 9.

I provided optimal solutions for both problems and concluded the interview early. The second problem can be solved with O(N) time complexity and O(1) space complexity.