SDE - 1

You are given an array 'a' of size 'n'.

Print the Next Greater Element(NGE) for every element.

The Next Greater Element for an element 'x' is the first element on the right side of 'x' in the array, which is greater than 'x'.

If no greater elements exist to the right of 'x', consider the next greater element as -1.

For example:

Input: 'a' = [7, 12, 1, 20]

Output: NGE = [12, 20, 20, -1]

Explanation: For the given array,

- The next greater element for 7 is 12.

- The next greater element for 12 is 20. 

- The next greater element for 1 is 20. 

- There is no greater element for 20 on the right side. So we consider NGE as -1.

You have been given an unsorted array ‘ARR’.

Your task is to sort the array in such a way that the array looks like a wave array.

Example:

If the given sequence ‘ARR’ has ‘N’ elements then the sorted wave array looks like - 
‘ARR[0] >= ARR[1]’ and ‘ARR[1] <= ARR[2]’
‘ARR[2] >= ARR[3]’ and ‘ARR[3] <= ARR[4]’
‘ARR[4] >= ARR[5]’ and ‘ARR[5] <= ARR[6]’  And so on.

Note:

1. ‘ARR[0]’ must be greater than or equal to ‘ARR[1]’.

2. There can be multiple arrays that look like a wave array but you have to return only one.

3. We have an internal function that will check your solution and return 'True' in case your array is one of the solutions otherwise return 'False'.

Explanation

The given array ‘ ARR = { 4, 3, 5, 2, 3, 1, 2 } ’
The below figure is a visual representation of the given ‘ARR’ and you can see we can express ‘ARR’ in a waveform array because 
4>3 and 3<5 
5>2 and 2<3
3>1 and 1<2
And it follows the condition of wave array.

Follow up:

Try to solve this problem in linear time complexity.

You have been given a circular array/list ‘ARR’ containing ‘N’ integers. You have to find out the maximum possible sum of a non-empty subarray of ‘ARR’.

A circular array is an array/list in which the end of the array connects to the beginning of the array.

A subarray may only include each element of the fixed buffer of ‘ARR’ at most once. (Formally, for a subarray ‘ARR[i]’, ‘ARR[i+1]’, ..., ‘ARR[j]’, there does not exist ‘i’ <= ‘k1’, ‘k2’ <= ‘j’ with ‘k1’ % ‘N’ = k2 % ‘N’.)

For Example:

The ‘ARR’ = [1, 2, -3, -4, 5], the subarray [5, 1, 2] has the maximum possible sum which is 8. This is possible as 5 is connected to 1 because ‘ARR’ is a circular array.

You have been given a circular path. There are N petrol pumps on this path that are numbered from 0 to N - 1 (Both inclusive). Each petrol pump has two values associated with it:

1)The amount of petrol that is available at this particular petrol pump.

2)The distance to reach the next petrol pump.

You are on a truck having an empty tank of infinite capacity. You can start the tour from any of the petrol pumps. Your task is to calculate the first petrol pump from where the truck will be able to complete the full circle or determine if it is impossible to do so.

You may assume that the truck will stop at every petrol pump and it will add the petrol from that pump to its tank. The truck will move one kilometre for each litre of petrol consumed.

What is your biggest achievement so far?

Where do you see yourself in 5 years?