Sequential & binary, linear search

What is searching?
• In computer science, searching is the process of finding an item with
specified properties from a collection of items.The items may be stored as
records in a database, simple data elements in arrays, text in files, nodes in
trees, vertices and edges in graphs, or maybe be elements in other search
place.

Why do we need searching?
• Searching is one of the core computer science algorithms. We know that
today’s computers store a lot of information.To retrieve this information
proficiently we need very efficient searching algorithms.

Binary Search
• Let us consider a problem of searching a word in a dictionary.Typically, we
directly go to some approximate page[say, middle page] start searching
from that point. If the name that we are searching is same then the search is
complete. If the page is before the selected pages then apply the process for
the first half otherwise apply the same process for the second half. Binary
search also works in the same way.The algorithm applying such strategy is
referred as binary search algorithm.

BINARY SEARCH
1 5 8 2412 36 48 876754
ENTER THE ARRAY ELEMENTS
ENTER THE NUMBER TO BE SEARCHED
36
M[0] M[1] M[2] M[3] M[4] M[5] M[6] M{7] M[8] M[9]

BINARY SEARCH
1 5 8 2412 36 48 876754
ENTER THE NUMBER TO BE SEARCHED 36
M[0] M[1] M[2] M[3] M[4] M[5] M[6] M{7] M[8] M[9]
LB UB

P=LB+UB/2
24
STEP 1
FIND THE MIDDLE ELEMENT
P=0+9/2

24 36<
36 48 54 67 87
THE SEARCH ELEMENT LIES IN THE UB
0 1 2 3 4
COMPARING SEARCH WITH MIDDLE ELEMENT
STEP 2

P=LB+UB/2 54
54 > 36
36 48
STEP 3
DIVIDE THE ARRAY FURTHER
COMPARING SEARCH WITH MIDDLE ELEMENT
THE SEARCH ELEMENT LIES IN THE LB

3636
=
NUMBER FOUND
STEP 4
36 48
MIDDLE ELEMENT IS COMPARED WITH THE ELEMENTS IN THE ARRAY

#include<stdio.h>
int main(){
int a[10],i,n,m,c=0,l,u,mid;
printf("Enter the size of an array: ");
scanf("%d",&n);
printf("Enter the elements in ascending order:
");
for(i=0;i<n;i++){
scanf("%d",&a[i]);
}
printf("Enter the number to be search: ");
scanf("%d",&m);
CODE

l=0,u=n-1;
while(l<=u){
mid=(l+u)/2;
if(m==a[mid]){
c=1;
break;
}
else if(m<a[mid]){
u=mid-1;
}
else
l=mid+1;
}
if(c==0)
printf("The number is not found.");
else
printf("The number is found.");
return 0;
}

Enter the elements of the array in ascending order
12
23
34
45
56
67
78
89
98
100
Enter the number to be searched
67
found

LINEAR SEARCH
10 46 8 996 2 34 19578
ENTER THE NUMBER TO BE SEARCHED
2
M[0] M[1] M[2] M[3] M[4] M[5] M[6] M{7] M[8] M[9]

LINEAR SEARCH
10 46 8 996 2 34 19578
2 2 2 2 2 2
THE NUMBER IS FOUND IN THE 6TH POSITION

#include <stdio.h>
int main()
{
int array[100], search, c, n;
printf("Enter the number of elements in arrayn");
scanf("%d",&n);
printf("Enter %d integer(s)n", n);
for (c = 0; c < n; c++)
scanf("%d", &array[c]);
CODE

printf("Enter the number to searchn");
scanf("%d", &search);
for (c = 0; c < n; c++)
{
if (array[c] == search) /* if required element found */
{
printf("%d is present at location %d.n", search, c+1);
break;
}
}
if (c == n)
printf("%d is not present in array.n", search);
return 0;
}

Sequential & binary, linear search

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