Suppose the Gas Station problem is modified so that you can refill gas multiple times at the same station (i.e., unlimited reuse), and you want to find if any start station allows completing the circle with this new rule. Which approach correctly adapts to this variant?
ACheck if total gas is at least total cost; if yes, return any station since reuse allows completion
BModify the algorithm to allow multiple passes over the stations until tank is non-negative
CUse a graph cycle detection algorithm to find a feasible cycle with unlimited refills
DUse the original greedy approach without changes; it still works correctly
Step-by-Step Solution
Solution:
Step 1: Understand unlimited refill effect
With unlimited refills, the only constraint is total gas >= total cost; any station can be start.
Step 2: Simplify solution
Since reuse removes the need to track tank drops, just check total gas vs cost and return any index if feasible.
Final Answer:
Option A -> Option A
Quick Check:
Unlimited refill means any station works if total gas suffices [OK]
Quick Trick:Unlimited refill means total gas check suffices [OK]
Common Mistakes:
MISTAKES
Trying to simulate multiple passes
Using original greedy without adaptation
Overcomplicating with graph algorithms
Trap Explanation:
PITFALL
Candidates may overcomplicate by simulating or searching cycles instead of simplifying to total gas check.
Interviewer Note:
CONTEXT
Tests if candidate can adapt algorithm to problem variants and reason about constraints.
Master "Gas Station (Circular)" in Greedy Algorithms
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