Drive the car
Submissions: 3961   Accuracy:


  Difficulty: Easy   Marks: 2

Suppose you are car driver and you have to drive a car on a track divided into "N" number of sub-tracks. You are also given the value of "K" i.e. the total kilometers the car can drive on each sub-track. If the car can't cover a sub-track, you can add any unit of Petrol in it. With each unit of petrol added, the total kilometers your car can travel will increase by one unit .

The first line of input contains an integer T denoting the no of test cases. Then T test cases follow. Each test case contains two lines of input. The first line contains two space separated integers N and K. The second line contains N space separated integers (A[])  denoting the distance of each N sub-tracks.

For each test case, you have to print out the minimum unit of Petrol your car requires to cover all the sub-tracks. If no extra unit of petrol is required, print -1.

1 <= T <= 100
1 <= N <= 107

1 <= K <= 1018
1 <= A[] <= 1018


5 7
2 5 4 5 2
5 4
1 6 3 5 2

Testcase 2: You are given 5 sub-tracks with different kilometers. Your car can travel 4 km on each sub-track. So, when you come on sub-track 2nd you have to cover 6 km of distance, so you need to have 2 unit of petrol more to cover the distance, for 3rd sub-track, now your car can travel 6 kilometers, so no problem and so on.

** For More Input/Output Examples Use 'Expected Output' option **

Contributor: Mohit Gupta
Author: Shubham Joshi 1

If you have purchased any course from GeeksforGeeks then please ask your doubt on course discussion forum. You will get quick replies from GFG Moderators there.

Need help with your code? Please use, generate link and share the link here.

to report an issue on this page.