eBay interview questions

Round 1 : (Hackerearth based test) [Time : 1h15m] This round had 2 questions. Given an array of size N and K queries, find the number of segments containing the index(from queires) which is leftmost or rightmost and the number at index is >= each elements of that segment Eg : arr[] = [1,2,3] K = [3] -> o/p : 3 ([3],[2,3][1,2,3]) Modification of this question(https://leetcode.com/problems/find-k-closest-elements/). Verdict: cleared Round 2 : F2F [Time : 1h] Given an array and a target sum k, find all a[i] + a[j] = k. Follow up: handle if the array has both duplicate and non-duplicate elements Find the first non-repeating character in the string (with only lowercase letters) https://leetcode.com/problems/first-unique-character-in-a-string/. Follow up : i ) contains both lowercase & uppercase ii) case-insensitive & case sensitive iii) in O(1) space complexity Verdict: cleared Round 3 : F2F [Time : 1h] Find if a linked list is a palindrome [expected time & space complexity : O(n) & O(1)]. https://leetcode.com/problems/palindrome-linked-list/ Find the diameter of the binary tree(https://leetcode.com/problems/diameter-of-binary-tree/) Validate if a tree is BST(https://leetcode.com/problems/validate-binary-search-tree/)