Find the longest path in a matrix where each step increases in value. You can only move up, down, left, or right.

Find the best pair of sightseeing spots in an array to maximize a score calculated from their values and distance. The score is the sum of the two spots' values minus the distance between them.

You are planning a meeting and need to invite the maximum number of employees. Employees have preferences for who they want to sit next to; find the largest group of employees who can be seated such that everyone is happy with their neighbors.