EX-7 Linear Search and Binary search

Date:

Aim:

To write a program to perform linear search and binary search using python programming.

Equipment’s required:

1. Hardware – PCs
2. Anaconda – Python 3.7 Installation / Moodle-Code Runner

Algorithm:

Linear Search:

1. Start from the leftmost element of array[] and compare k with each element of array[] one by one.
2. If k matches with an element in array[] , return the index.
3. If k doesn’t match with any of elements in array[], return -1 or element not found.

Binary Search:

1. Set two pointers low and high at the lowest and the highest positions respectively.
2. Find the middle element mid of the array ie. arr[(low + high)/2]
3. If x == mid, then return mid.Else, compare the element to be searched with m.
4. If x > mid, compare x with the middle element of the elements on the right side of mid. This is done by setting low to low = mid + 1.
5. Else, compare x with the middle element of the elements on the left side of mid. This is done by setting high to high = mid - 1.
6. Repeat steps 2 to 5 until low meets high

Program:

i)	Use a linear search method to match the item in a list.
def linearsearch(array,n,k):
    for i in range(0,n):
        if(array[i]==k):
            return i
    return -1
array = eval(input())
k=eval(input())
n=len(array)
array.sort()
result = linearsearch(array,n,k)
if(result==-1):
    print(array)
    print("Element not found")
else:
    print(array)
    print("Element found at index: ",result)





ii)	Find the element in a list using Binary Search(Iterative Method).

def linearsearch(array,n,k):
    for i in range(0,n):
        if(array[i]==k):
            return i
    return -1
array = eval(input())
k=eval(input())
n=len(array)
array.sort()
result = linearsearch(array,n,k)
if(result==-1):
    print(array)
    print("Element not found")
else:
    print(array)
    print("Element found at index: ",result)





iii)	 Find the element in a list using Binary Search (recursive Method).

def BinarySearch(arr, k, low, high):
    if high>=low:
        mid=low+(high-low)//2
        if arr[mid]==k:
            return mid
        elif arr[mid]>k:
            return BinarySearch(arr,k,low,mid-1)
        else:
            return BinarySearch(arr,k,mid+1,high)
    else:
        return -1
arr=eval(input())
arr.sort()
k=eval(input())
result = BinarySearch(arr,k,0,len(arr)-1)
if(result==-1):
    print(arr)
    print("Element not found")
else:
    print(arr)
    print("Element found at index: ",result)

Sample Input and Output

Result

Thus the linear search and binary search algorithm is implemented using python programming.