Interviewer asked about background for 10 mins. Then moved to ask question:

Given a 2d matrix that represents a matrix where . denotes empty land, c indicates car, and o indicates oasis, and another integer gas which indicates gas we have left. Traversing one unit in the matrix consumes 1 gas unit. You can move up, down, left, and right.
So Example: the matrix below and gas = 5 returns true since we can get from c to o in 5 units (1 unit left, 3 units down, and 1 unit right)
[[. . . c .]
[. . . . .]
[. . . . .]
[ . . o . .]]

a) Check if car can reach oasis or not. (return bool val)
b) Now suppose there is a gas station in the matrix somewhere that is denoted by an integer k where k represents the gas units that the car will be refuelled. So if k is 2, car will gain gas. Check if car can still reach oasis (with or without gas station).

^This was the part that confused me.

c) Now let's say there's obstacles in the matrix represented by r. how would you check if car can reach oasis? (Answered dfs with memoization)

Would really appreciate if someone can share their approach to this problem! (preferrably in Python)