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* added ceaserCipher algorithm * added ceaserCipher algorithm * fixed a typo

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src/algorithms/string/caeserCipher
- README.md
- __test__
  - caeserCipher.test.js
- caeserCipher.js

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	`1`	`+# caeserCipher Algorithm`
	`2`	`+`
	`3`	`+caeserCipher Algorithm is a type of substitution algorithm in which each letter in the plaintext is replaced by a letter some fixed number of positions down the alphabet. For example, with a left shift of 3, D would be replaced by A, E would become B, and so on`
	`4`	`+`
	`5`	`+## Complexity`
	`6`	`+`
	`7`	+- Time: `O(\|n\|)`
	`8`	+- Space: `O(\|n\|)`
	`9`	`+## Example`
	`10`	`+`
	`11`	+The the following string `abcde` which is shifted by 1 will change to `bcdef`
	`12`	`+`
	`13`	`+## References`
	`14`	`+`
	`15`	`+- [Wikipedia](https://en.wikipedia.org/wiki/Caesar_cipher)`

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	`1`	`+import caeserCipher from '../caeserCipher';`
	`2`	`+`
	`3`	`+describe('caeserCipher', () => {`
	`4`	`+ it('should subtitute each character by shifting up the alphabet by a given integer', () => {`
	`5`	`+`
	`6`	`+`
	`7`	`+ expect(caeserCipher('abcd', 1)).toBe('bcde');`
	`8`	`+ });`
	`9`	`+`
	`10`	`+`
	`11`	`+ it('should wrap back to the beginning of the alphabet if it shifts more than the 26 english alphabets', () => {`
	`12`	`+`
	`13`	`+`
	`14`	`+ expect(caeserCipher('xyz', 1)).toBe('yza');`
	`15`	`+ });`
	`16`	`+ it('should only shift letters and ignore non-alphabetic characters', () => {`
	`17`	`+`
	`18`	`+ expect(caeserCipher('gurer ner 9 qbtf!', 13)).toBe('there are 9 dogs!');`
	`19`	`+ });`
	`20`	`+`
	`21`	`+ it('should ignore case sensitivity', () => {`
	`22`	`+`
	`23`	`+ expect(caeserCipher('ABCD', 13)).toBe('bcde');`
	`24`	`+ });`
	`25`	`+`
	`26`	`+`
	`27`	`+})`

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	`1`	`+/**`
	`2`	`+ * @param {string} string`
	`3`	`+ * @param {number} shift`
	`4`	`+ * @return {string} result`
	`5`	`+ */`
	`6`	`+`
	`7`	`+export default function caeserCipher(string, shift) {`
	`8`	`+ // convert all alphabets in english language to an array`
	`9`	`+ const alphabetArr = "abcdefghijklmnopqrstuvwxyz".split("")`
	`10`	`+ // converting all the alphabets in string to lowercase`
	`11`	`+ string = string.toLowerCase()`
	`12`	`+`
	`13`	`+ let result = ""`
	`14`	`+ for (let i = 0; i < string.length; i++) {`
	`15`	`+ const currentChar = string[i]`
	`16`	`+ // checking index of character in the english alphabets`
	`17`	`+ const idx = alphabetArr.indexOf(currentChar)`
	`18`	`+ // skip character if the character is not an alphabet`
	`19`	`+ if (idx === -1) {`
	`20`	`+ result += currentChar`
	`21`	`+ continue;`
	`22`	`+ }`
	`23`	`+ //wrap up index, incase the next shift is beyond the 26th character`
	`24`	`+ const encodedIdx = (idx + shift) % 26`
	`25`	`+ result += alphabetArr[encodedIdx]`
	`26`	`+`
	`27`	`+ }`
	`28`	`+ // return the result of the shifted string`
	`29`	`+ return result`
	`30`	`+}`

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