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$ curl repovive.com/roadmaps/pattern-22/greedy/gas-station-implementation

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$ curl repovive.com/roadmaps/pattern-22/greedy/gas-station-implementation

Repovive

LeetCode 134 Gas Station - Implementation - Greedy | Pattern 22: LeetCode Interview Patterns | Repovive

Repovive.

Pattern 22: LeetCode Interview Patterns24 sections · 736 units32h total

Open in Course

LeetCode 134 Gas Station - Implementation

The approach

Single pass. Reset start when tank goes negative.

def canCompleteCircuit(gas, cost): totalTank = currTank = 0 start = 0

for i in range(len(gas)):
    totalTank += gas[i] - cost[i]
    currTank += gas[i] - cost[i]
    if currTank < 0:
        start = i + 1
        currTank = 0

return start if totalTank >= 0 else -1

$O(n)$ time, $O(1)$ space.