A-M baby

Task/Levenshtein-distance/Java/levenshtein-distance-2.java

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+public class Levenshtein{
+    public static int levenshtein(String s, String t){
+        /* if either string is empty, difference is inserting all chars
+         * from the other
+         */
+        if(s.length() == 0) return t.length();
+        if(t.length() == 0) return s.length();
+
+        /* if first letters are the same, the difference is whatever is
+         * required to edit the rest of the strings
+         */
+        if(s.charAt(0) == t.charAt(0))
+            return levenshtein(s.substring(1), t.substring(1));
+
+        /* else try:
+         *      changing first letter of s to that of t,
+         *      remove first letter of s, or
+         *      remove first letter of t
+         */
+        int a = levenshtein(s.substring(1), t.substring(1));
+        int b = levenshtein(s, t.substring(1));
+        int c = levenshtein(s.substring(1), t);
+
+        if(a > b) a = b;
+        if(a > c) a = c;
+
+        //any of which is 1 edit plus editing the rest of the strings
+        return a + 1;
+    }
+
+    public static void main(String[] args) {
+        String s1 = "kitten";
+        String s2 = "sitting";
+        System.out.println("distance between '" + s1 + "' and '"
+                + s2 + "': " + levenshtein(s1, s2));
+        s1 = "rosettacode";
+        s2 = "raisethysword";
+        System.out.println("distance between '" + s1 + "' and '"
+                + s2 + "': " + levenshtein(s1, s2));
+        StringBuilder sb1 = new StringBuilder(s1);
+        StringBuilder sb2 = new StringBuilder(s2);
+        System.out.println("distance between '" + sb1.reverse() + "' and '"
+                + sb2.reverse() + "': "
+                + levenshtein(sb1.reverse().toString(), sb2.reverse().toString()));
+    }
+}