From 1e4f0df9681fe24c6d10b086e98a83d56d810638 Mon Sep 17 00:00:00 2001
From: Jaime Martinez Rincon <mrjaime1999@gmail.com>
Date: Sat, 14 Jan 2017 01:20:14 +0100
Subject: [PATCH] Improved the LevenshteinDistance class

---
 .../utils/LevenshteinDistance.java            | 104 +++++++-----------
 1 file changed, 38 insertions(+), 66 deletions(-)

diff --git a/src/main/java/me/jaimemartz/lobbybalancer/utils/LevenshteinDistance.java b/src/main/java/me/jaimemartz/lobbybalancer/utils/LevenshteinDistance.java
index ca78e65..c9c6094 100644
--- a/src/main/java/me/jaimemartz/lobbybalancer/utils/LevenshteinDistance.java
+++ b/src/main/java/me/jaimemartz/lobbybalancer/utils/LevenshteinDistance.java
@@ -1,87 +1,59 @@
 package me.jaimemartz.lobbybalancer.utils;
 
 public class LevenshteinDistance {
-    public static String getClosestString(String input, String[] options) {
-        int lowestDistance = 10;
-        String lowest = "";
+    public static <T> T closest(Iterable<T> collection, T target) {
+        int distance = Integer.MAX_VALUE;
+        T closest = null;
 
-        for (String string : options) {
-            int distance = getLevenshteinDistance(input, string);
-            if (distance < lowestDistance) {
-                lowestDistance = distance;
-                lowest = string;
+        for (T object : collection) {
+            int current = distance(object.toString(), target.toString());
+            if (current < distance) {
+                distance = current;
+                closest = object;
             }
         }
 
-        return lowest;
+        return closest;
     }
 
-    public static String getClosestString(String input, Iterable<String> options) {
-        int lowestDistance = 10;
-        String lowest = "";
+    private static int distance(CharSequence lhs, CharSequence rhs) {
+        int len0 = lhs.length() + 1;
+        int len1 = rhs.length() + 1;
 
-        for (String string : options) {
-            int distance = getLevenshteinDistance(input, string);
-            if (distance < lowestDistance) {
-                lowestDistance = distance;
-                lowest = string;
-            }
-        }
+        // the array of distances
+        int[] cost = new int[len0];
+        int[] newcost = new int[len0];
 
-        return lowest;
-    }
+        // initial cost of skipping prefix in String s0
+        for (int i = 0; i < len0; i++) cost[i] = i;
 
-    private static int getLevenshteinDistance(String s, String t) {
-        if (s == null || t == null) {
-            return 11;
-        }
+        // dynamically computing the array of distances
 
-        int n = s.length();
-        int m = t.length();
+        // transformation cost for each letter in s1
+        for (int j = 1; j < len1; j++) {
+            // initial cost of skipping prefix in String s1
+            newcost[0] = j;
 
-        if (n == 0) {
-            return m;
-        } else if (m == 0) {
-            return n;
-        }
+            // transformation cost for each letter in s0
+            for (int i = 1; i < len0; i++) {
+                // matching current letters in both strings
+                int match = (lhs.charAt(i - 1) == rhs.charAt(j - 1)) ? 0 : 1;
 
-        if (n > m) {
-            String tmp = s;
-            s = t;
-            t = tmp;
-            n = m;
-            m = t.length();
-        }
+                // computing cost for each transformation
+                int cost_replace = cost[i - 1] + match;
+                int cost_insert = cost[i] + 1;
+                int cost_delete = newcost[i - 1] + 1;
 
-        int p[] = new int[n + 1];
-        int d[] = new int[n + 1];
-        int _d[];
-
-        int i;
-        int j;
-
-        char t_j;
-
-        int cost;
-
-        for (i = 0; i <= n; i++) {
-            p[i] = i;
-        }
-
-        for (j = 1; j <= m; j++) {
-            t_j = t.charAt(j - 1);
-            d[0] = j;
-
-            for (i = 1; i <= n; i++) {
-                cost = s.charAt(i - 1) == t_j ? 0 : 1;
-                d[i] = Math.min(Math.min(d[i - 1] + 1, p[i] + 1), p[i - 1] + cost);
+                // keep minimum cost
+                newcost[i] = Math.min(Math.min(cost_insert, cost_delete), cost_replace);
             }
 
-            _d = p;
-            p = d;
-            d = _d;
+            // swap cost/newcost arrays
+            int[] swap = cost;
+            cost = newcost;
+            newcost = swap;
         }
 
-        return p[n];
+        return cost[len0 - 1];
     }
-}
\ No newline at end of file
+}