Good evening! Here's our prompt for today.

We are given two strings order and str, with the string order already sorted in a custom order. Permute the characters of str such that they match the custom order in which order is sorted. More specifically, if a character x occurs before a character y in order, then x should occur before y in the permuted string.

For example, consider the following strings as input:

1const order = 'fed';
2const str = 'adef';

The output for the given string will be "feda". "d", "e", "f" in str are arranged according to the order string, which makes the order of "d", "e", "f" as "f", "e", "d". Since "a" does not appear in the defined order, it should appear at the end of the string.

Constraints

• 1 <= order.length <= 26
• 1 <= s.length <= 200
• order and s consist of lowercase English letters.
• All the characters of order are unique.

Try to solve this here or in Interactive Mode.

How do I practice this challenge?

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var assert = require('assert');

​

function custom_sort_string(order, s) {

    //fill in the solution

    return;

}

​

try {

    assert.equal(custom_sort_string('fed', 'adef'), 'feda');

​

    console.log('PASSED: ' + "custom_sort_string('fed', 'adef') should return `feda`");

} catch (err) {

    console.log(err);

}

​

try {

    assert.equal(custom_sort_string('cba', 'abcd'), 'cbad');

​

    console.log('PASSED: ' + "custom_sort_string('cba', 'abcd') should return `cbad`");

} catch (err) {

    console.log(err);

}

​

try {

    assert.equal(custom_sort_string('cbafg', 'abcd'), 'cbad');

​

    console.log('PASSED: ' + "custom_sort_string('cbafg', 'abcd') should return `cbad`");

} catch (err) {

    console.log(err);

Here's our guided, illustrated walk-through.

How do I use this guide?