Problems to test your OOPS skill!

MARS ROVER PROBLEM

A squad of robotic rovers are to be landed by NASA on a plateau on Mars. This plateau, which is curiously rectangular, must be navigated by the rovers so that their on-board cameras can get a complete view of the surrounding terrain to send back to Earth. A rover’s position and location is represented by a combination of x and y co-ordinates and a letter representing one of the four cardinal compass points. The plateau is divided up into a grid to simplify navigation. An example position might be 0, 0, N, which means the rover is in the bottom left corner and facing North. In order to control a rover, NASA sends a simple string of letters. The possible letters are ‘L’, ‘R’ and ‘M’. ‘L’ and ‘R’ makes the rover spin 90 degrees left or right respectively, without moving from its current spot. ‘M’ means move forward one grid point, and maintain the same heading. Assume that the square directly North from (x, y) is (x, y+1).

INPUT:
The first line of input is the upper-right coordinates of the plateau, the lower-left coordinates are assumed to be 0,0. The rest of the input is information pertaining to the rovers that have been deployed. Each rover has two lines of input. The first line gives the rover’s position, and the second line is a series of instructions telling the rover how to explore the plateau. The position is made up of two integers and a letter separated by spaces, corresponding to the x and y co-ordinates and the rover’s orientation. Each rover will be finished sequentially, which means that the second rover won’t start to move until the first one has finished moving.

OUTPUT
The output for each rover should be its final co-ordinates and heading.

INPUT AND OUTPUT

Test Input:
5 5
1 2 N
LMLMLMLMM
3 3 E
MMRMMRMRRM

Expected Output:
1 3 N
5 1 E
==========

GAME OF LIFE PROBLEM

The universe of the Game of Life is an infinite two-dimensional orthogonal grid of square cells, each of which is in one of two possible states, live or dead. Every cell interacts with its eight neighbours, which are the cells that are directly horizontally, vertically, or diagonally adjacent. At each step in time, the following transitions occur:

Any live cell with fewer than two live neighbours dies, as if by loneliness.

Any live cell with more than three live neighbours dies, as if by overcrowding.

Any live cell with two or three live neighbours lives, unchanged, to the next generation.

Any dead cell with exactly three live neighbours comes to life.

The initial pattern constitutes the 'seed' of the system. The first generation is created by applying the above rules Simultaneously to every cell in the seed — births and deaths happen simultaneously, and the discrete moment at which this happens is sometimes called a tick. (In other words, each generation is a pure function of the one before.) The rules continue to be applied repeatedly to create further generations.
 Problem:
The inputs below represent the cells in the universe as X or - . X is a alive cell. - is a dead cell or no cell. The below inputs provide the provide pattern or initial cells in the universe. The output is the state of the system in the next tick (one run of the application of all the rules), represented in the same format.

-------------------------------------------------------------------------------------------
Input A:
(Block pattern)
     X X
     X X
                                         
Output A:
     X X
     X X

-------------------------------------------------------------------------------------------
Input B
(Boat pattern)
X X -
X - X
- X -

Output B
X X -
X - X
- X -

-------------------------------------------------------------------------------------------
Input C
(Blinker pattern)
     - X -
     - X -
     - X -

Output C
     - - -
     X X X
     - - -

-------------------------------------------------------------------------------------------
Input D
(Toad pattern)
        - X X X
        X X X -

Output D
        - - X -
        X - - X
        X - - X
        - X - -

==============================================

SALES TAXES PROBLEM

Basic sales tax is applicable at a rate of 10% on all goods, except books, food, and medical products that

are exempt. Import duty is an additional sales tax applicable on all imported goods at a rate of 5%, with

no exemptions.

When I purchase items I receive a receipt which lists the name of all the items and their price (including

tax), finishing with the total cost of the items, and the total amounts of sales taxes paid. The rounding

rules for sales tax are that for a tax rate of n%, a shelf price of p contains (np/100 rounded up to the

nearest 0.05) amount of sales tax.

Write an application that prints out the receipt details for these shopping baskets...

INPUT:

Input 1:

1 book at 12.49

1 music CD at 14.99

1 chocolate bar at 0.85

Input 2:

1 imported box of chocolates at 10.00

1 imported bottle of perfume at 47.50

Input 3:

1 imported bottle of perfume at 27.99

1 bottle of perfume at 18.99

1 packet of headache pills at 9.75

1 box of imported chocolates at 11.25

OUTPUT

Output 1:

1 book : 12.49

1 music CD: 16.49

1 chocolate bar: 0.85

Sales Taxes: 1.50

Total: 29.83

Output 2:

1 imported box of chocolates: 10.50

1 imported bottle of perfume: 54.65

Sales Taxes: 7.65

Total: 65.15

Output 3:

1 imported bottle of perfume: 32.19

1 bottle of perfume: 20.89

1 packet of headache pills: 9.75

1 imported box of chocolates: 11.85

Sales Taxes: 6.70

Total: 74.68

Association, Aggregation, Composition, Abstraction, Generalization, Realization, Dependency

Association

Association is a relationship between two objects. In other words, association defines the multiplicity between objects. You may be aware of one-to-one, one-to-many, many-to-one, many-to-many all these words define an association between objects. Aggregation is a special form of association. Composition is a special form of aggregation.

Example: A Student and a Faculty are having an association.

Aggregation

Aggregation is a special case of association. A directional association between objects. When an object ‘has-a’ another object, then you have got an aggregation between them. Direction between them specified which object contains the other object. Aggregation is also called a “Has-a” relationship.

Composition

Composition is a special case of aggregation. In a more specific manner, a restricted aggregation is called composition. When an object contains the other object, if the contained object cannot exist without the existence of container object, then it is called composition.

Example: A class contains students. A student cannot exist without a class. There exists composition between class and students.

Difference between aggregation and composition

Composition is more restrictive. When there is a composition between two objects, the composed object cannot exist without the other object. This restriction is not there in aggregation. Though one object can contain the other object, there is no condition that the composed object must exist. The existence of the composed object is entirely optional. In both aggregation and composition, direction is must. The direction specifies, which object contains the other object.

Example: A Library contains students and books. Relationship between library and student is aggregation. Relationship between library and book is composition. A student can exist without a library and therefore it is aggregation. A book cannot exist without a library and therefore its a composition. For easy understanding I am picking this example. Don’t go deeper into example and justify relationships!

Abstraction

Abstraction is specifying the framework and hiding the implementation level information. Concreteness will be built on top of the abstraction. It gives you a blueprint to follow to while implementing the details. Abstraction reduces the complexity by hiding low level details.

Example: A wire frame model of a car.

Generalization

Generalization uses a “is-a” relationship from a specialization to the generalization class. Common structure and behaviour are used from the specializtion to the generalized class. At a very broader level you can understand this as inheritance. Why I take the term inheritance is, you can relate this term very well. Generalization is also called a “Is-a” relationship.

Example: Consider there exists a class named Person. A student is a person. A faculty is a person. Therefore here the relationship between student and person, similarly faculty and person is generalization.

Realization

Realization is a relationship between the blueprint class and the object containing its respective implementation level details. This object is said to realize the blueprint class. In other words, you can understand this as the relationship between the interface and the implementing class.

Example: A particular model of a car ‘GTB Fiorano’ that implements the blueprint of a car realizes the abstraction.

Dependency

Change in structure or behaviour of a class affects the other related class, then there is a dependency between those two classes. It need not be the same vice-versa. When one class contains the other class it this happens.

Example: Relationship between shape and circle is dependency.

Abstraction Vs Encapsulation

Abstraction refers to the act of representing essential features without including the background details or explanation.

This is achieved in java by
- Abstract Class and Interface

- Hiding information by access modifier only give access to required
- Object - Nothing can be accessed by Object ref.

Encapsulation means wrapping up of data and methods into a single unit (Class).

Encapsulation is part of abstraction. It protects abstractions.

A real world example,

Consider you have setup a big building(say a company), the details regarding materials used to built (glass, bricks), type of work, manager of the company, number of floors, design of the building, cost of the building etc. can be classified as ABSTRACTION.

Whereas, type of glass or bricks (grey one or red one) used, who all work for which all departments n how they work, cost of each and every element in the building etc. comes under data ENCAPSULATION.