added nextGreaterElement.c

[darshanhande11]

Fixes #732

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[theyashshahs]

@darshanhande11 provide a short video or screenshot for your implementation

[darshanhande11]

@iiitv/project-maintainers

Problem Statement

Given an array, print the Next Greater Element (NGE) for every element. The Next greater Element for an element x is the first greater element on the right side of x in array. Elements for which no greater element exist, consider next greater element as -1.

Examples:

1. For any array, rightmost element always has next greater element as -1.
2. For an array which is sorted in decreasing order, all elements have next greater element as -1.
3. For the input array [4, 5, 2, 25}, the next greater elements for each element are as follows.

I have attached the output screenshots which explains the implementation.

[theyashshahs]

@ishanksoni please review the PR

[darshanhande11]

@ishanksoni Sir, I have added the time and space complexity as comment in the code. Please let me know if any changes are to be done.