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The Apache Commons Codec package contains simple encoder and decoders for various formats such as Base64 and Hexadecimal. In addition to these widely used encoders and decoders, the codec package also maintains a collection of phonetic encoding utilities.

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/*   Copyright 2004 The Apache Software Foundation
 *
 *   Licensed under the Apache License, Version 2.0 (the "License");
 *   you may not use this file except in compliance with the License.
 *   You may obtain a copy of the License at
 *
 *       http://www.apache.org/licenses/LICENSE-2.0
 *
 *   Unless required by applicable law or agreed to in writing, software
 *   distributed under the License is distributed on an "AS IS" BASIS,
 *   WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
 *   See the License for the specific language governing permissions and
 *  limitations under the License.
 */

package org.apache.xmlbeans.impl.common;

public class Levenshtein
{
    //****************************
    // Get minimum of three values
    //****************************

    private static int minimum(int a, int b, int c)
    {
        int mi = a;
        if (b < mi)
            mi = b;
        if (c < mi)
            mi = c;
        return mi;
    }

    //*****************************
    // Compute Levenshtein distance
    //*****************************
    public static int distance(String s, String t)
    {
        int d[][]; // matrix
        int n; // length of s
        int m; // length of t
        int i; // iterates through s
        int j; // iterates through t
        char s_i; // ith character of s
        char t_j; // jth character of t
        int cost; // cost

        // Step 1
        n = s.length();
        m = t.length();
        if (n == 0)
            return m;
        if (m == 0)
            return n;
        d = new int[n+1][m+1];

        // Step 2
        for (i = 0; i <= n; i++)
            d[i][0] = i;
        for (j = 0; j <= m; j++)
            d[0][j] = j;

        // Step 3
        for (i = 1; i <= n; i++)
        {
            s_i = s.charAt (i - 1);

            // Step 4
            for (j = 1; j <= m; j++)
            {
                t_j = t.charAt(j - 1);

                // Step 5
                if (s_i == t_j)
                    cost = 0;
                else
                    cost = 1;

                // Step 6
                d[i][j] = minimum(d[i-1][j]+1, d[i][j-1]+1, d[i-1][j-1] + cost);
            }
        }

        // Step 7
        return d[n][m];
    }

}