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63 lines
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1.9 KiB
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63 lines
No EOL
1.9 KiB
Markdown
# Binary Search
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Welcome to Binary Search on Exercism's Elixir Track.
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If you need help running the tests or submitting your code, check out `HELP.md`.
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## Instructions
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Implement a binary search algorithm.
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Searching a sorted collection is a common task. A dictionary is a sorted
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list of word definitions. Given a word, one can find its definition. A
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telephone book is a sorted list of people's names, addresses, and
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telephone numbers. Knowing someone's name allows one to quickly find
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their telephone number and address.
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If the list to be searched contains more than a few items (a dozen, say)
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a binary search will require far fewer comparisons than a linear search,
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but it imposes the requirement that the list be sorted.
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In computer science, a binary search or half-interval search algorithm
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finds the position of a specified input value (the search "key") within
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an array sorted by key value.
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In each step, the algorithm compares the search key value with the key
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value of the middle element of the array.
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If the keys match, then a matching element has been found and its index,
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or position, is returned.
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Otherwise, if the search key is less than the middle element's key, then
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the algorithm repeats its action on the sub-array to the left of the
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middle element or, if the search key is greater, on the sub-array to the
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right.
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If the remaining array to be searched is empty, then the key cannot be
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found in the array and a special "not found" indication is returned.
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A binary search halves the number of items to check with each iteration,
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so locating an item (or determining its absence) takes logarithmic time.
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A binary search is a dichotomic divide and conquer search algorithm.
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## Source
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### Created by
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- @bernardoamc
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### Contributed to by
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- @angelikatyborska
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- @Cohen-Carlisle
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- @devonestes
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- @lpil
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- @martinsvalin
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- @neenjaw
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- @parkerl
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- @screamingjungle
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- @sotojuan
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- @waiting-for-dev
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### Based on
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Wikipedia - http://en.wikipedia.org/wiki/Binary_search_algorithm |