The Tower of Hanoi is a mathematical game or puzzle. It consists of three rods, and a number of disks of different sizes which can slide onto any rod. The puzzle starts with the disks in a neat stack in ascending order of size on one rod, the smallest at the top, thus making a conical shape.

The objective of the puzzle is to move the entire stack to another rod, obeying the following simple rules:

1. Only one disk can be moved at a time.
2. Each move consists of taking the upper disk from one of the stacks and placing it on top of another stack i.e. a disk can only be moved if it is the uppermost disk on a stack.
3. No disk may be placed on top of a smaller disk.

With three disks, the puzzle can be solved in seven moves. The minimum number of moves required to solve a Tower of Hanoi puzzle is 2ⁿ – 1, where n is the number of disks.

(Via Wikipedia)

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A stack is an abstract data type that serves as a collection of elements, with two principal operations:

1. push adds an element to the collection
2. pop removes the last element that was added.

It is a LIFO (Last In First Out) kind of data structure. That means the element which added at last will be taken out first.

Singly linked lists contain nodes which have a data field as well as a ‘next’ field, which points to the next node in line of nodes. Operations that can be performed on singly linked lists include insertion, deletion and traversal.

(via Wikipedia)

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Here is java implementation of queue using linked list.

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Quick Sort is sorting algorithm based on divide and conquer method. For more information about quick sort you can check this and this post.

Infix notation is the notation commonly used in arithmetical and logical formulae and statements. It is characterized by the placement of operators between operands – “infixed operators” – such as the plus sign in “2 + 2”.

Reverse Polish notation (RPN) or PostFix Notation is a mathematical notation in which every operator follows all of its operands such as the plus sign in “2 2 +”.