1. Introduction
to
Data Structure
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2. Algorithm
● An algorithm is a finite set of instructions
which, when followed, accomplishes a
particular task.
● Its Characteristics
○ Each instruction should be unique and concise
○ Each instruction should be relative in nature
and should not be repeated infinitely.
○ Repetition of same task(s) should be avoided.
○ The result be available to the user after the
algorithm terminates.
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3. Efficiency of Algorithms
● The performance of algorithms can be
measured on the scales
● Time
● Space
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4. Space Complexity
● The amount of memory space required by the
algorithm during the course of execution
● Some of the reasons for space complexity are
○ If the program, is to run on mutli-user system, it may be
required to specify the amount of memory to be allocated
to the program
○ We may be interested to know in advance that whether
sufficient memory is available to run the program.
○ There may be several possible solutions with different
space requirements.
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5. Space needed by Program Components
● Instruction Space – Space needed to
store the executable version of the
program and it is fixed.
● Data Space : It is needed to store all
constants, varialbe values
● Environment Space : Space needed to
store the information needed to resume
the suspended functions.
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6. Time Complexity
● The amount of time needed to run to
completion.
● Some reasons for studying time
complexity
○ We may be interested to know in
advance that whether a program will
provide satisfactory real time response.
○ There must be several possible solutions
with different time requirements.
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7. Data structure
● When elements of data are organized together in
terms of some relationships among the elements,
the organization is called data structure.
● A data structure is a set of data values along with
the relationship between the data values in form
of set of operations permitted on them.
● Arrays, records, stacks, lists, graphs are the
names of some of some of these basic data
structures.
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8. A data structure can be
(a) transient
i.e. it is created when a program starts and is destroyed
when the program ends. Most data structures in main
memory are transient, for example, an array of data.
(b) Permanent
i.e. it already exists when a program starts and is
preserved when the program ends. Most data structures on
disk are permanent, for example, a file of data, or a cross-
linked data file collection (a database).
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9. Data Structure
Linear Non-Linear
● Array ● Tree
● Stack ● Graph
● Queue
● Linked
Lists
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10. Abstract Data Type (ADT)
● It is a mathematical model with a collections of
operations defined on that model.
● The ADT encapsulates a data type can be
localized and are not visible to the users of the
ADT.
● An implementation of an ADT is a translation into
statements of a programming language, of the
declaration that defines a variable to be of that
ADT, plus a procedure in that language for each
operation of the ADT.
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