Gas Station

Hard~25 min

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. If there is no solution, return -1. If a solution exists, it is guaranteed to be unique.

Examples

Example 1

Input: gas = [1,2,3,4,5], cost = [3,4,5,1,2]

Output: 3

Explanation: Start at station 3. Tank = 0+4=4. Go to 4: 4-1+5=8. Go to 0: 8-2+1=7. Go to 1: 7-3+2=6. Go to 2: 6-4+3=5. Go to 3: 5-5=0. Complete circuit.

Example 2

Input: gas = [2,3,4], cost = [3,4,3]

Output: -1

Explanation: Total gas (9) < total cost (10), so no solution exists.

Constraints

n == gas.length == cost.length
1 <= n <= 10^5
0 <= gas[i], cost[i] <= 10^4
Expected time complexity: O(n)

Code

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Output

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