Add README files 1/7 (#5754)

* Added 5 README files

* corrected arithmetic_analysis README

* Update audio_filters/README.md

Co-authored-by: John Law <johnlaw.po@gmail.com>

* Update backtracking/README.md

Co-authored-by: John Law <johnlaw.po@gmail.com>

* Update bit_manipulation/README.md

Co-authored-by: John Law <johnlaw.po@gmail.com>

Co-authored-by: John Law <johnlaw.po@gmail.com>

arithmetic_analysis/README.md

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+# Arithmetic analysis
+
+Arithmetic analysis is a branch of mathematics that deals with solving linear equations.
+
+* <https://en.wikipedia.org/wiki/System_of_linear_equations>
+* <https://en.wikipedia.org/wiki/Gaussian_elimination>
+* <https://en.wikipedia.org/wiki/Root-finding_algorithms>

audio_filters/README.md

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+# Audio Filter
+
+Audio filters work on the frequency of an audio signal to attenuate unwanted frequency and amplify wanted ones.
+They are used within anything related to sound, whether it is radio communication or a hi-fi system.
+
+* <https://www.masteringbox.com/filter-types/>
+* <http://ethanwiner.com/filters.html>
+* <https://en.wikipedia.org/wiki/Audio_filter>
+* <https://en.wikipedia.org/wiki/Electronic_filter>

backtracking/README.md

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+# Backtracking
+
+Backtracking is a way to speed up the search process by removing candidates when they can't be the solution of a problem.
+
+* <https://en.wikipedia.org/wiki/Backtracking>
+* <https://en.wikipedia.org/wiki/Decision_tree_pruning>
+* <https://medium.com/@priyankmistry1999/backtracking-sudoku-6e4439e4825c>
+* <https://www.geeksforgeeks.org/sudoku-backtracking-7/>

bit_manipulation/README.md

@@ -1,6 +1,11 @@
-* https://docs.python.org/3/reference/expressions.html#binary-bitwise-operations
-* https://docs.python.org/3/reference/expressions.html#unary-arithmetic-and-bitwise-operations
-* https://docs.python.org/3/library/stdtypes.html#bitwise-operations-on-integer-types
-* https://wiki.python.org/moin/BitManipulation
-* https://wiki.python.org/moin/BitwiseOperators
-* https://www.tutorialspoint.com/python3/bitwise_operators_example.htm
+# Bit manipulation
+
+Bit manipulation is the act of manipulating bits to detect errors (hamming code), encrypts and decrypts messages (more on that in the 'ciphers' folder) or just do anything at the lowest level of your computer.
+
+* <https://en.wikipedia.org/wiki/Bit_manipulation>
+* <https://docs.python.org/3/reference/expressions.html#binary-bitwise-operations>
+* <https://docs.python.org/3/reference/expressions.html#unary-arithmetic-and-bitwise-operations>
+* <https://docs.python.org/3/library/stdtypes.html#bitwise-operations-on-integer-types>
+* <https://wiki.python.org/moin/BitManipulation>
+* <https://wiki.python.org/moin/BitwiseOperators>
+* <https://www.tutorialspoint.com/python3/bitwise_operators_example.htm>

boolean_algebra/README.md

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+# Boolean Algebra
+
+Boolean algebra is used to do arithmetic with bits of values True (1) or False (0).
+There are three basic operations: 'and', 'or' and 'not'.
+
+* <https://en.wikipedia.org/wiki/Boolean_algebra>
+* <https://plato.stanford.edu/entries/boolalg-math/>