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# Chapter 11 - Introduction to Data Structure and Algorithms

###### tags: `Data Structure and Algorithms`

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## Learning objectives
By the end of this chapter, you should able to:
1. Defind data strctures and algorithms

## Algorithm and Pseudocode

The term “algorithm” means, in computer science, the step by step method of solving a problem. Pseudocode is the most common method to define an algorithm, which is an English-like and syntax-free representation of algorithm logic. Below shows an example of pseudocode that prints the deviation.

Algorithm deviation
   Pre    nothing
   Post   average and numbers with their deviation printed
 1 loop (not end of file)
   1  read number into array
   2  add number to total
   3  increment count
 2 end loop
 3 set average to total / count
 4 print average
 5 loop (not end of array)
   1  set devFromAve to array element - average
   2  print array element and devFromAve
 6 end loop
end deviation

There are two points worth mentioning in the above algorithm. First, there are no parameters. Second, as previously explained, we do not declare variables. A variable’s type and purpose should be easily determined by its name and usage.

In the later chapters, we will focus on two kinds of algorithms, namely *sorting* and *searching*.

## Data Strcutures

A *data structure* is an aggregation of atomic and composite data into a set with defined relationships. In this definition, *structure* means a set of rules that holds the data together. In other words, if we take a* combination of data and fit them into a structure* such that we can define its related rules, we have made a data structure.

Below shows some examples of data structures.


### Abstract data type model

An abstract data type (ADT) is a data declaration packaged together with the operations that are meaningful for the data type. Inside the ADT are two different aspects of the model: data structures and functions (public and private). Below shows the ADT model in diagram.

In this series, we will learn both *array-implementation* and *linked-list implementation* data structures. We will focus on three types of data structures, namely *linked list*, *stack* and *queue*.


## Learning path

In the coming chapters, we will focus on the data structures and algorithms mentioned. Below is our learning path on data structure and algorithm.