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CreatePermutations.js
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CreatePermutations.js
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/*
a permutation of a set is, loosely speaking, an arrangement of its members into a sequence or linear order, or if the set is already ordered, a rearrangement of its elements.
The word "permutation" also refers to the act or process of changing the linear order of an ordered set
More at : https://en.wikipedia.org/wiki/Permutation
*/
const createPermutations = (str) => {
// convert string to array
const arr = str.split('')
// get array length
const strLen = arr.length
// this will hold all the permutations
const perms = []
let rest
let picked
let restPerms
let next
// if strLen is zero, return the same string
if (strLen === 0) {
return [str]
}
// loop to the length to get all permutations
for (let i = 0; i < strLen; i++) {
rest = Object.create(arr)
picked = rest.splice(i, 1)
restPerms = createPermutations(rest.join(''))
for (let j = 0, jLen = restPerms.length; j < jLen; j++) {
next = picked.concat(restPerms[j])
perms.push(next.join(''))
}
}
return perms
}
export { createPermutations }