How should I practice Gas Station?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Bloomberg LP phone screen and onsite interview problems in FastPrep.

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Gas Station

Bloomberg LP● MediumNEW GRADPHONE SCREENONSITE INTERVIEW

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Problem statement

There are n gas stations on a circular route. gas[i] is the fuel available at station i, and cost[i] is the fuel needed to travel from station i to station (i + 1) mod n.

You start with an empty tank. Return the index of the station from which you can travel clockwise around the circuit exactly once without the tank becoming negative. Return -1 if no such station exists. If a solution exists, it is unique.

Function

canCompleteCircuit(gas: int[], cost: int[]) → int

Examples

Example 1

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

Starting at station 3, the tank never becomes negative and returns to station 3 after visiting every station.

Example 2

gas = [2,3,4]cost = [3,4,3]return = -1

Total available fuel is less than the total travel cost, so no start can complete the circuit.

Example 3

gas = [5]cost = [4]return = 0

The single station supplies enough fuel for its only leg.

Constraints

1 <= n == gas.length == cost.length <= 100000.
0 <= gas[i], cost[i] <= 10000.
If a valid starting station exists, it is unique.