Data Structure is a way of collecting and organising data in such a way that we can perform operations on these data in an effective way. Data Structures is about rendering data elements in terms of some relationship, for better organization and storage. For example, we have data player's name "Virat" and age 26. Here "Virat" is of String data type and 26 is of integer data type.
We can organize this data as a record like Player record. Now we can collect and store player's records in a file or database as a data structure. For example: "Dhoni" 30, "Gambhir" 31, "Sehwag" 33
In simple language, Data Structures are structures programmed to store ordered data, so that various operations can be performed on it easily. It represents the knowledge of data to be organized in memory. It should be designed and implemented in such a way that it reduces the complexity and increases the effieciency.
As we have discussed above, anything that can store data can be called as a data structure, hence Integer, Float, Boolean, Char etc, all are data structures. They are known as Primitive Data Structures.
Then we also have some complex Data Structures, which are used to store large and connected data. Some example of Abstract Data Structure are :
All these data structures allow us to perform different operations on data. We select these data structures based on which type of operation is required. We will look into these data structures in more details in our later lessons.
The data structures can also be classified on the basis of the following characteristics:
|Linear||In Linear data structures,the data items are arranged in a linear sequence. Example: Array|
|Non-Linear||In Non-Linear data structures,the data items are not in sequence. Example: Tree, Graph|
|Homogeneous||In homogeneous data structures,all the elements are of same type. Example: Array|
|Non-Homogeneous||In Non-Homogeneous data structure, the elements may or may not be of the same type. Example: Structures|
|Static||Static data structures are those whose sizes and structures associated memory locations are fixed, at compile time. Example: Array|
|Dynamic||Dynamic structures are those which expands or shrinks depending upon the program need and its execution. Also, their associated memory locations changes. Example: Linked List created using pointers|
An algorithm is a finite set of instructions or logic, written in order, to accomplish a certain predefined task. Algorithm is not the complete code or program, it is just the core logic(solution) of a problem, which can be expressed either as an informal high level description as pseudocode or using a flowchart.
Every Algorithm must satisfy the following properties:
An algorithm is said to be efficient and fast, if it takes less time to execute and consumes less memory space. The performance of an algorithm is measured on the basis of following properties :
Its the amount of memory space required by the algorithm, during the course of its execution. Space complexity must be taken seriously for multi-user systems and in situations where limited memory is available.
An algorithm generally requires space for following components :
Time Complexity is a way to represent the amount of time needed by the program to run till its completion. We will study this in details in later sections.
NOTE: Before going deep into data structure, you should have a good knowledge of programming either in C or in C++ or Java.