Design HashMap

Design a HashMap without using any built-in hash table libraries. To be specific, your design should include these functions:

Add Two Numbers

Given two number represent by LinkedList, calculate the sum of the numbers and store the result in a new LinkedList. Each node of the linked list is represented by single-digit and the head node is the most significant digit.

Invert Binary Tree

Inverting a Binary Tree is a problem asked in a lot of interviews and we will be tackling it in a simple but efficient manner. Any tree-related problem should be attempted to be solved in a recursive approach since Tree is a localized data structure i.e small trees make up large trees.

Isomorphic Strings

Given two strings s and t, determine if they are isomorphic. Two strings are isomorphic if the characters in s can be replaced to get t. All occurrences of a character must be replaced with another character while preserving the order of characters. No two characters may map to the same character but a character may map to itself.