COMPUTER PROGRAMMING

Lecture 06

Prepared By Mr. V. S. Patil Dept (CSE)/AEC

Unit 1 Problem SolvingSyllabus

Prepared By Mr. V. S. Patil Dept (CSE)/AEC

2

1Understanding Linear Search

Understanding Binary Search

Objectives

Linear Search: A Simple Search

•A search traverses the collection until

–The desired element is found

–Or the collection is exhausted

•If the collection is ordered, I might not have to look at all

elements

–I can stop looking when I know the element cannot be in

the collection.

Algorithm of Linear search

(Linear Search) LINEAR(DATA, N, ITEM, LOC)

Here DATA is an linear array with N element and ITEM is a given

item of information .This algorithm find the location LOC of ITEM

in the DATA or Sets LOC:=0. IF Search is unsuccessful.

1. [Insert ITEM at the end of DATA].

Set DATA[N+1]:=ITEM

2. [Initialize counter] set LOC:=1

1

2

Continue..

3. [Search for item].

Repeat while DATA[LOC]=!ITEM

Set LOC:=LOC+1

[End of loop]

4 [Successful?] if LOC=N+1 then:

Set LOC:=0.

Exit

3

4

5

Linear Search

7 12 5 22 13 32DATA

1 2 3 4 5 6

DATA

7 12 5 22 13 32

1 2 3 4 5 6

7 12 5 22 13 32

1 2 3 4 5 6

7 12 5 22 13 32

1 2 3 4 5 6

ITEM= 13

7 12 5 22 13 32

1 2 3 4 5 6

Item Found at LOC=5

DATA

DATA

DATA

Video of linear search

• View video

Binary Search

•BINARY(DATA, N, ITEM, Lo, Hi, Mid)

Here DATA is an array with N element and ITEM is a given

item of information .This algorithm find the location ITEM in

the DATA.

1.Initially Lo=0 and Hi= N+1

2.Find Mid=(Lo+Hi)/2

3.If(ITEM<Mid)

4.Hi=Mid-1

5.Repeat step 2

Continue..

6. If(ITEM>Mid)

7. Lo=Lo+Mid

8. Repeat step 2

9. if(mid==ITEM)

10.ITEM found at Mid

11. Else ITEM not in list

12.Stop

Binary Search

• (Binary search. Given value and sorted array a[ ], find index isuch that a[i] = value, or report that no such index exists.

• Invariant. Algorithm maintains a[lo] value a[hi].• Ex. Binary search for 33.

Binary Search

Binary Search

Binary Search

ITEM= 33 Found at 4th position

Binary search video

Question Bank

1. What is mean by searching?

• Explain linear search with suitable example

1. With the help of binary search algorithm find 7 in given list.

12 45 34 67 98 42 23 7 87