SDE - 1

You are given a string ('STR') of length 'N'. Find the longest palindromic substring. If there is more than one palindromic substring with the maximum length, return the one with the smaller start index.

Note:

A substring is a contiguous segment of a string.

For example : The longest palindromic substring of "ababc" is "aba", since "aba" is a palindrome and it is the longest substring of length 3 which is a palindrome, there is another palindromic substring of length 3 is "bab" since "aba" starting index is less than "bab", so "aba" is the answer.

Given an array of numbers, find the maximum sum of any contiguous subarray of the array.

For example, given the array [34, -50, 42, 14, -5, 86], the maximum sum would be 137, since we would take elements 42, 14, -5, and 86.

Given the array [-5, -1, -8, -9], the maximum sum would be -1.

Follow up: Do this in O(N) time.

You have been given a Binary Tree of distinct integers and two nodes ‘X’ and ‘Y’. You are supposed to return the LCA (Lowest Common Ancestor) of ‘X’ and ‘Y’.

The LCA of ‘X’ and ‘Y’ in the binary tree is the shared ancestor of ‘X’ and ‘Y’ that is located farthest from the root.

Note :

You may assume that given ‘X’ and ‘Y’ definitely exist in the given binary tree.

For example :

For the given binary tree

LCA of ‘X’ and ‘Y’ is highlighted in yellow colour.