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JarviixAll problems

Gas Station

Medium

Greedy · Array~20m

Live AI Interview

00:00

Section 1Understand Problem

Section 01

Understand the problem

Restate the problem precisely. Interviewers reward candidates who pause, define the contract, and name the guarantees before coding.

Problem statement

There are `n` gas stations along a circular route, where the amount of gas at the i-th station is `gas[i]`. You have a car with an unlimited gas tank and it costs `cost[i]` of gas to travel from the i-th station to its next (i + 1)-th station. You begin the journey with an empty tank at one of the gas stations. Given two integer arrays `gas` and `cost`, return the starting gas station's index if you can travel around the circuit once in the clockwise direction, otherwise return `-1`. If there exists a solution, it is guaranteed to be unique.

Example

gas = [1,2,3,4,5], cost = [3,4,5,1,2] → 3

Constraints

n == gas.length == cost.length · 1 ≤ n ≤ 10⁵ · 0 ≤ gas[i], cost[i] ≤ 10⁴

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AI Review

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