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Merged
itsvinayak merged 2 commits into from
May 6, 2020
Merged

Create palindrome algorithm #134

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588b03e
Create palindrome algorithm
NourBc May 1, 2020
c124a0c
Update Palindrome.js
itsvinayak May 6, 2020
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51 changes: 51 additions & 0 deletions maths/Palindrome.js
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/**
* A palindrome is any string that can be reversed and still be the same.
* An example of one is 'radar', since it is spelled the same even after
* being reversed. One method to check if a
*
* Here's how this works recursively:
*
* Palindrome('radar')
* true && Palindrome('ada')
* true && true && Palindrome('d')
* true && true && true && true
*
* @flow
* @complexity: O(n)
*/

function PalindromeRecursive (string) {
// Base case
if (string.length < 2) return true

// Check outermost keys
if (string[0] !== string[string.length - 1]) {
return false
}

return PalindromeRecursive(string.slice(1, string.length - 1))
}

function PalindromeIterative (string) {
const _string = string
.toLowerCase()
.replace(/ /g, '')
.replace(/,/g, '')
.replace(/'.'/g, '')
.replace(/:/g, '')
.split('')

// A word of only 1 character is already a palindrome, so we skip to check it
while (_string.length > 1) {
if (_string.shift() !== _string.pop()) {
return false
}
}

return true
}

// testing

console.log(PalindromeRecursive('Javascript Community'))
console.log(PalindromeIterative('mom'))