Get minimum length string to break a lock

minimum_unlock_stream.js

function generateStream(len, alphabet) {
    alphabet = alphabet || [0,1]
    var hash = {};
    var str = '';
    for (var i=0;i<len;i++) {
        str += alphabet[0];
    }
    hash[str] = 1;
    while (true) {
        var currString = str.substring(str.length-len+1);
        for (var i=alphabet.length-1; i>=0; i--) {
            var nextString = currString + alphabet[i];
            if (!hash[nextString]) {
                hash[nextString] = 1;
                str += alphabet[i];
                break;
            }
        }
        if (i==-1) {
            break;
        }
    }
    return str;
}


generateStream(4, [0,1,2,3,4,5,6,7,8,9]);