{ "data": { "question": { "questionId": "134", "questionFrontendId": "134", "boundTopicId": null, "title": "Gas Station", "titleSlug": "gas-station", "content": "
There are n
gas stations along a circular route, where the amount of gas at the ith
station is gas[i]
.
You have a car with an unlimited gas tank and it costs cost[i]
of gas to travel from the ith
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
\n
Example 1:
\n\n\nInput: gas = [1,2,3,4,5], cost = [3,4,5,1,2]\nOutput: 3\nExplanation:\nStart at station 3 (index 3) and fill up with 4 unit of gas. Your tank = 0 + 4 = 4\nTravel to station 4. Your tank = 4 - 1 + 5 = 8\nTravel to station 0. Your tank = 8 - 2 + 1 = 7\nTravel to station 1. Your tank = 7 - 3 + 2 = 6\nTravel to station 2. Your tank = 6 - 4 + 3 = 5\nTravel to station 3. The cost is 5. Your gas is just enough to travel back to station 3.\nTherefore, return 3 as the starting index.\n\n\n
Example 2:
\n\n\nInput: gas = [2,3,4], cost = [3,4,3]\nOutput: -1\nExplanation:\nYou can't start at station 0 or 1, as there is not enough gas to travel to the next station.\nLet's start at station 2 and fill up with 4 unit of gas. Your tank = 0 + 4 = 4\nTravel to station 0. Your tank = 4 - 3 + 2 = 3\nTravel to station 1. Your tank = 3 - 3 + 3 = 3\nYou cannot travel back to station 2, as it requires 4 unit of gas but you only have 3.\nTherefore, you can't travel around the circuit once no matter where you start.\n\n\n
\n
Constraints:
\n\nn == gas.length == cost.length
1 <= n <= 105
0 <= gas[i], cost[i] <= 104
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