Find a repeating command program for a vehicle under fuel and memory limits

A vehicle on a grid starts at a given cell with 100 fuel. Each move up, down, left or right costs one unit; at a station it can refuel 50 units; obstacles block movement. It can store at most ten commands and repeats its program forever. Find a short program that meets the goal the interviewer sets (for example, reaching a target without running out of fuel), and explain how you search the space of programs.