9. Palindrome Number

String

4. Median Of Two Sorted Arrays

2. Add Two Numbers

Linked List

Valid Parentheses

HashTable Stack

1. Two Sum

Array HashTable

DoublyLinkedList Design (with bidirectional search to perform faster)

Node.next - Value - Node.prev Actions: addAtHead, addAtTail, get, deleteAt, addAtIndex

Linked List

CTCI 1.4 Palindrome Permutation

String

CTCI 1.6 String Compression

Count the chars using loop

Array String