Linear Search problem practice In DSA

Linear Search — Practice Problems in Data structures & algorithms (DSA)

Practice Sheet: Applying Linear Search to common array problems

Goal: Learn how to scan an array from left to right and apply Linear Search to find a first index, check presence, count occurrences, find all indexes, and find a maximum value.

Problem 1 — Find First Index

Given the array [15, 8, 22, 10, 7, 22] and target 22.

•  Return the first index of 22.

•  Expected answer: 2

Problem 2 — Check Presence

Given the array [4, 9, 12, 6, 18, 3] and target 15.

•  Return True if 15 is present.

•  Return False if 15 is not present.

•  Expected answer: False

Problem 3 — Count Occurrences

Given the array [5, 2, 5, 8, 5, 9, 2] and target 5.

•  Return the number of occurrences of 5.

•  Expected answer: 3

Problem 4 — Find All Indexes

Given the array [3, 7, 3, 10, 3, 5, 3] and target 3.

•  Return all indexes where 3 occurs.

•  Expected answer: [0, 2, 4, 6]

Problem 5 — Find Maximum

Given the array [12, 45, 7, 89, 23, 56].

•  Use the Linear Search approach to find the maximum element.

•  Return the maximum element.

•  Expected answer: 89

How to Practice These Problems

Use the same simple process for each problem:

Step	What to do
1. Understand	Identify the array and the target/requirement.
2. Apply Linear Search	Check elements from left to right.
3. Record the result	Depending on the question, save the first index, True/False, count, all indexes, or maximum.
4. Code it	Write the solution yourself in Python.
5. Check complexity	For a basic Linear Search solution, time is generally O(n); extra space is generally O(1), except when the task requires storing multiple indexes/results.

Important: If the question asks only whether an element is present, you can stop when the first match is found. If it asks for the count or all indexes, you must continue checking the whole array.

 

Answer:

from array import*

arr=array('i',[12,5,8,20,15,7])

for x in arr:

    if x==20:

        print("yes 20 present in array",arr.index(20))

        break

    else:

        print("not present")

       

arr1=array('i', [15,8,22,10,7,22])

print("The first index of 22 is",arr1.index(22))

 

arr2=array('i',[4,9,12,6,18,3])

for i in range(len(arr2)):

    if i==15:

        print("if present")

    else:print("if not present")

 

arr3=array('i',[5,2,5,8,5,9,2,5,5])

print("The number of occurrence of 5 is",arr3.count(5))

count=0

for co in arr3:

    if co==5:

     count=count+1

print("the number of occurnce of 5 is",count)  

 

 

arr4=array('i',[3,7,3,10,3,5,3])

count=0

a=[]

for index,co in enumerate(arr4):

    if co==3:

     count=count+1

     a.append(index)

print("the number of occurnce of 3 is",count)

print("index of 3 is",a)

 

arr5=array('i',[12,45,7,89,23,56])

print(max(arr5))

print(sorted(arr5)[len(sorted(arr5))-1])