public int computeEditDistance(String s1, String s2) {
        s1 = s1.toLowerCase();
        s2 = s2.toLowerCase();

        int[] costs = new int[s2.length() + 1];
        for (int i = 0; i <= s1.length(); i++) {
            int lastValue = i;
            for (int j = 0; j <= s2.length(); j++) {
                if (i == 0)
                    costs[j] = j;
                else {
                    if (j > 0) {
                        int newValue = costs[j - 1];
                        if (s1.charAt(i - 1) != s2.charAt(j - 1))
                            newValue = Math.min(Math.min(newValue, lastValue),
                                    costs[j]) + 1;
                        costs[j - 1] = lastValue;
                        lastValue = newValue;
                    }
                }
            }
            if (i > 0)
                costs[s2.length()] = lastValue;
        }
        return costs[s2.length()];
    }