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Classics #10
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Classics #10
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12f9ba2
--update: initial implementation
ashokdey c376de5
--fix: edge case of upper case alphabet
ashokdey c801b3e
--fix: missing case for -ve new index
ashokdey 76b9ace
--update: final implementation
ashokdey 408dc13
--fix: spell fix
ashokdey 479e925
--update: get pair of index for two numbers sum to N
ashokdey 20280c8
--update: replaced indexof with Map(), throw error on missing arguments
ashokdey c2eec66
--update: added fibonacci
ashokdey dbd3dbd
--update: added optimized fibonacci using cache
ashokdey 8a9d8b8
--update: 32-bit signed int reversal
ashokdey f04d86c
--fix: removed outdated files
ashokdey 602df1f
--fix-conflict: got files from master
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47 changes: 47 additions & 0 deletions
src/_Classics_/caeser_cipher/index.js
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| Original file line number | Diff line number | Diff line change |
|---|---|---|
| @@ -0,0 +1,47 @@ | ||
| /** | ||
| * Most simplest encryption scheme. Read more: [http://practicalcryptography.com/ciphers/caesar-cipher/] | ||
| * @param {String} str | ||
| * @param {Number} num | ||
| */ | ||
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| function caeserCipher(str, num) { | ||
| const lowerCaseString = str.toLowerCase(); | ||
| const alphabets = 'abcdefghijklmnopqrstuvwxyz'.split(''); | ||
| const totalAlphabets = alphabets.length; | ||
| let result = ''; | ||
|
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| // handle large number, like 300 or -300 | ||
| num %= totalAlphabets; | ||
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| for (let index in lowerCaseString) { | ||
| // get the current character | ||
| const currentCharacter = lowerCaseString[index]; | ||
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| // if character is space, add it to the result and continue to next | ||
| if (currentCharacter === ' ') { | ||
| result += currentCharacter; | ||
| continue; | ||
| } | ||
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| // determine the new index | ||
| const currentIndex = alphabets.indexOf(currentCharacter); | ||
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| let newIndex = currentIndex + num; | ||
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| // if the index passes 25, restart from 0 | ||
| if (newIndex > totalAlphabets - 1) { | ||
| newIndex -= totalAlphabets; | ||
| } | ||
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| if (newIndex < 0) { | ||
| newIndex = totalAlphabets + newIndex; | ||
| } | ||
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| // check if the character in original string was upper case | ||
| if (str[index] === str[index].toUpperCase()) { | ||
| result += alphabets[newIndex].toUpperCase(); | ||
| } else { | ||
| result += alphabets[newIndex]; | ||
| } | ||
| } | ||
| return result; | ||
| } | ||
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