The selection process consisted of three stages:

• Two online assessments:
  • The first online assessment included general core computer science questions and a coding question.
  • The second round focused entirely on coding.
• Two face-to-face interviews:
  • The third round involved medium-level data structures and algorithms questions.
  • The fourth round assessed behavioral aspects.

You are given an m x n grid where each cell can have one of three values:

• 0 representing an empty cell
• 1 representing a fresh orange
• 2 representing a rotten orange

Every minute, any fresh orange that is 4-directionally adjacent to a rotten orange becomes rotten. Return the minimum number of minutes that must elapse until no cell has a fresh orange. If this is impossible, return -1.