Acoustic77 Acoustic77 - 1 year ago 113
Javascript Question

Recursively print all permutations of a string (Javascript)

I've seen versions of this question for other languages, but not for JS.

Is it possible to do this recursively in one function?

I understand that I need to take the first element in the string, and then append it to each solution to the recursion on the remainder of the string.
So logically, I understand how the recursion needs to go. I just don't understand how to append the first char onto each of the recursive solutions

var myString = "xyz";

function printPermut(inputString){
var outputString;
if(inputString.length === 0){
return inputString;
if(inputString.length === 1){
return inputString;
for(int i = 0; i<inputString.length(); i++){
//something here like:
//outputString = outputString.concat(printPermut(inputString.slice(1))??
//maybe store each unique permutation to an array or something?

Answer Source

So, lets write a function, that returns all permutations of a string as an array. As you don't want any global variables, returning the permutations is crucial.

function permut(string) {
    if (string.length < 2) return string; // This is our break condition

    var permutations = []; // This array will hold our permutations

    for (var i=0; i<string.length; i++) {
        var char = string[i];

        // Cause we don't want any duplicates:
        if (string.indexOf(char) != i) // if char was used already
            continue;           // skip it this time

        var remainingString = string.slice(0,i) + string.slice(i+1,string.length); //Note: you can concat Strings via '+' in JS

        for (var subPermutation of permut(remainingString))
            permutations.push(char + subPermutation)

    return permutations;

To print them, just iterate over the array afterwards:

var myString = "xyz";
permutations = permut(myString);
for (permutation of permutations)
    print(permutation) //Use the output method of your choice

Hope, I could help you with your question.

Greets, Syntac

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