find longest common non-contiguous subsequence

longest non-contiguous subsequence

var fs = require("fs");

var a, b, split,
    longest = '',
    sequence = '',
    output = '',
    matched = 0,
    matchpos = 0;

fs.readFileSync(process.argv[2]).toString().split('\n').forEach(function(line) {
    sequence = '';
    if (!line) {
        return;
    }
    var split = line.split(';');
    a = reverse(split[0]);
    b = reverse(split[1]);

    console.log(getseq(a, b)); //output answer
});

function getseq(one, two) {

    if (one === '' || two === '') {
        return reverse(sequence);
    }

    if (one.charAt(0) === two.charAt(0)) { //matching character, save
        sequence += one.charAt(0);
        return getseq(one.substr(1), two.substr(1));
    } else {
        var nexta = one.charAt(0);
        var nextb = two.charAt(0);
        var matchFound = false;

        if (!contains(one, nextb)) {
            return getseq(one, two.substr(two.indexOf(nextb) + 1));
        } else {
            matchFound = true;
        }
        if (!contains(two, nexta)) {
            return getseq(one.substr(one.indexOf(nexta) + 1), two);
        } else {
            matchFound = true;
        }

        if (!matchFound) { //neither have char, eat both
            return getseq(one.substr(1), two.substr(1));
        }
        if (two.indexOf(nexta) < one.indexOf(nextb)) {
            return getseq(one, two.substr(1));
        } else {
            return getseq(one.substr(1), two);
        }
    }
}

function contains(owner, char) {
    return owner.indexOf(char) !== -1;
}

function reverse(str) {
    return str.split("").reverse().join("");
}