Levenshtein.java

/*
 * *
 *  * This file is part of QuickLyric
 *  * Copyright © 2017 QuickLyric SPRL
 *  *
 *  * QuickLyric is free software: you can redistribute it and/or modify
 *  * it under the terms of the GNU General Public License as published by
 *  * the Free Software Foundation, either version 3 of the License, or
 *  * (at your option) any later version.
 *  *
 *  * QuickLyric is distributed in the hope that it will be useful,
 *  * but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  * GNU General Public License for more details.
 *  * You should have received a copy of the GNU General Public License
 *  * along with QuickLyric.  If not, see <http://www.gnu.org/licenses/>.
 *
 */

package com.geecko.QuickLyric.utils;

import java.util.Locale;

public class Levenshtein {

    public static int distance(String a, String b) {
        a = a.toLowerCase(Locale.US);
        b = b.toLowerCase(Locale.US);
        // i == 0
        int [] costs = new int [b.length() + 1];
        for (int j = 0; j < costs.length; j++)
            costs[j] = j;
        for (int i = 1; i <= a.length(); i++) {
            // j == 0; nw = lev(i - 1, j)
            costs[0] = i;
            int nw = i - 1;
            for (int j = 1; j <= b.length(); j++) {
                int cj = Math.min(1 + Math.min(costs[j], costs[j - 1]), a.charAt(i - 1) == b.charAt(j - 1) ? nw : nw + 1);
                nw = costs[j];
                costs[j] = cj;
            }
        }
        return costs[b.length()];
    }

}