JavaScript-Interview-Questions/recursion/007.js at master · pramock4bs/JavaScript-Interview-Questions

209 lines (191 loc) · 2.27 KB

 *  This program is distributed under
 *  the terms of the MIT license.
 *  Please see the LICENSE file for details.
 * Implement a routine that prints all the permutations of a given string.
 * Do *not* use recursion.
/*____________________________________________________________________________*/
 * @function {public static} swap
 * Swaps the two characters of a given string.
 * @param {String} str - the `String` to swap.
 * @param {Integer} i - the first character index.
 * @param {Integer} j - the second character index.
 * @return the swapped `String`.
function swap(str, i, j) {
    var ar = str.split('');
    var temp = ar[i];
    ar[i] = ar[j];
    ar[j] = temp;
    return ar.join('');
 * A helper.
function print(str) {
    console.log(str);
 * @function {public static} permute
 * Iteratively permutes the `String` using
 * the "CountDown QuickPerm Algorithm".
 * ref: http://permute.tchs.info/01example.php
 * @param {String} str - the `String` to permute.
function permute(str) {
    var len = str.length;
    var p = [];
    for(var i=0; i<len+1; i++) {
        p[i] = i;
    var i = 1;
    var j = 0;
    print(str);
    while (i < len) {
        p[i] -= 1;
        j = (i%2 === 0) ? 0 : p[i];
        str = swap(str, j, i);
        print(str);
        i = 1;
        while (p[i] === 0) {
            p[i] = i;
            i++;
/*____________________________________________________________________________*/
permute('SF_CA');
Output: ($ /usr/bin/node 007.js)

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