Gas Tank Problem Statement

You have a car with a gas tank of infinite capacity. There are 'N' gas stations located along a circular route, numbered from 0 to N-1. You begin your journey with an empty tank from one of these stations. The objective is to complete one full clockwise traversal around the circular route. That means if you start from station 'i', you will pass through i+1, i+2, ..., N-1, 0, 1, ..., i-1, and finally return back to 'i'.

You are provided with two integer arrays, gas and cost. The element gas[i] indicates the amount of gas available at station 'i', and cost[i] denotes the amount of gas required to travel from station 'i' to the next station (i.e., station i+1, or 0 if station is N-1).

Your task is to find the starting gas station's index that allows you to complete the circle once. If there are multiple potential starting points, select the smallest index. If completing the circle isn't possible from any starting point, return -1.

Example:

Input:

T = 1
N = 5
gas = [1, 2, 3, 4, 5]
cost = [3, 4, 5, 1, 2]

Output:

3

Explanation:

Starting at station 3, the car can complete a full circle as it accumulates enough gas to travel each segment.

Constraints:

• 1 <= T <= 50
• 1 <= N <= 10⁴
• 0 <= GAS[i] <= 10⁵
• 0 <= COST[i] <= 10⁵