Linear Search Aqa

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Exam code:8525

Linear Search

What is a searching algorithm?

Searching algorithms are precise step-by-step instructions that a computer can follow to efficiently locate specific data in massive datasets
Two common searching algorithms are:
- Binary search
- Linear search

What is a linear search?

A linear search starts with the first value in a dataset and checks every value one at a time until all values have been checked
A linear search can be performed even if the values are not in order

How do you perform a linear search?

Step	Instruction
1	Check the first value
2	IF it is the value you are looking for STOP!
3	ELSE move to the next value and check
4	REPEAT UNTIL you have checked all values and not found the value you are looking for

Examiner Tips and Tricks

You will not be asked to perform a linear search on a dataset in the exam, you will be expected to understand how to do it and know the advantages and disadvantages compared to a binary search

Worked Example

A linear search could be used instead of a binary search.

Describe the steps a linear search would follow when searching for a number that is not in the given list [2]

Answer

Starting with the first value
Checking all values in order

Guidance

Must cover idea of checking all value AND being done in order!
“Checks each value from the beginning to the end” implies order so would get both bullet point 1 & 2

A linear search in python

# Identify the dataset to search, the target value and set the initial flag
data = [5, 2, 8, 1, 9]
target = 11
found = False

# Loop through each element in the data
for index in range(0,len(data) - 1):

# Check if the current element matches the target
if data[index] == target:
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# If found, output message
found = True
print("Target found")

#If the target is not found, output a message
if found is False:
print("Target not found")

Computer Science GCES AQA