No Repeats Please

No repeats please!

Overview

Instructions

Return the number of total permutations of the provided string that don’t have repeated consecutive letters. Assume that all characters in the provided string are each unique.

For example, aab should return 2 because it has 6 total permutations (aab, aab, aba, aba, baa, baa), but only 2 of them (aba and aba) don’t have the same letter (in this case a) repeating.

My Approach

Code:

function permute(a, n = a.length) {
    var c = [];
    var result = [];
    for (var i = 0; i < n; i++) {
        c[i] = 0;
    }
    result.push(a);
    var i = 0;
    while (i < n) {
        if (c[i] < i) {
            if (i % 2 === 0) {
                var split = a.split('');
                const temp0 = a[0];
                const tempi = a[i];
                split[0] = tempi;
                split[i] = temp0;
                var a = split.join("");
            } else {
                var split = a.split('');
                const temp0 = a[c[i]];
                const tempi = a[i];
                split[c[i]] = tempi;
                split[i] = temp0;
                var a = split.join("");
            }
            result.push(a);
            c[i] += 1
            i = 0

        } else {
            c[i] = 0
            i += 1
        }
    }
    return result;
}

function permAlone(str) {
    a = str;
    var permArray = permute(a);
    permArray = permArray.filter(function (pattern) {
        for (var i = 0; i <= pattern.length - 1; i++) {
            if (pattern[i] === pattern[i + 1]) {
                return false;
            }
        }

        return true;
    });

    return permArray.length;
}

console.log(permAlone("aab"));
console.log(permAlone("zzzdd"));
console.log(permAlone("abfcdef"));