SDE - Intern

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.

You are given two Singly Linked Lists of integers, which may have an intersection point.

Your task is to return the first intersection node. If there is no intersection, return NULL.

Example:-

The Linked Lists, where a1, a2, c1, c2, c3 is the first linked list and b1, b2, b3, c1, c2, c3 is the second linked list, merging at node c1.

There are ‘N’ people at a party. Each person has been assigned a unique id between 0 to 'N' - 1(both inclusive). A celebrity is a person who is known to everyone but does not know anyone at the party.

Given a helper function ‘knows(A, B)’, It will returns "true" if the person having id ‘A’ know the person having id ‘B’ in the party, "false" otherwise. Your task is to find out the celebrity at the party. Print the id of the celebrity, if there is no celebrity at the party then print -1.

Note:

1. The helper function ‘knows’ is already implemented for you.
2. ‘knows(A, B)’ returns "false", if A doesn't know B.
3. You should not implement helper function ‘knows’, or speculate about its implementation.
4. You should minimize the number of calls to function ‘knows(A, B)’.
5. There are at least 2 people at the party.
6. At most one celebrity will exist.