Searching Algorithms

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With a partner play the Higher or lower game? start from 0 to 10, then 0 to 50 and then 0 to 100 and finally 0 to 500

Search Algorithms

What are search algorithms and why do we need them?

Often on your smart phone you might search for:

a contact in order to call me
a business or group on social media
a location on a map

Computers store a massive amount of information, and it would be impractical (if not impossible) to look for all the data we need manually. This means that computers need to be able to search through information to find it. What method the computer uses is known as the search algorithm.

Linear Search

A linear search algorithm is an algorithm that starts at the beginning of a list and goes through each item in the list, looking for a match.

Advantages

Very simple
Can be using on sorted or unsorted lists

Disadvantages

Very slow

OCR GCSE 2.1 Linear search.mp4

Binary Search

A binary search algorithm is an algorithm that starts in the centre of a list and finds out of the value is greater or less than the value at the mid point (or if it is the value!)

The unused part of the list it then discarded and the process begins all over again.

Advantages

Very Fast, even with massive data sets

Disadvantages

Can only be used with sorted lists

OCR GCSE 2.1 Binary search.mp4

Activity – Search Poster

Using Google Draw create a poster that clearly explain why we need to search data? what is the difference between binary and linear searches and also the advantages and the disadvantages of each type of search method.

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