diff --git a/lesson_13/maps_java/maps_app/src/main/java/com/codedifferently/lesson13/Lesson13.java b/lesson_13/maps_java/maps_app/src/main/java/com/codedifferently/lesson13/Lesson13.java
index 0c981abb..40f0831f 100644
--- a/lesson_13/maps_java/maps_app/src/main/java/com/codedifferently/lesson13/Lesson13.java
+++ b/lesson_13/maps_java/maps_app/src/main/java/com/codedifferently/lesson13/Lesson13.java
@@ -1,5 +1,7 @@
 package com.codedifferently.lesson13;
 
+import java.util.HashMap;
+
 public class Lesson13 {
 
   /**
@@ -7,6 +9,18 @@ public class Lesson13 {
    * https://leetcode.com/problems/permutation-difference-between-two-strings
    */
   public int findPermutationDifference(String s, String t) {
-    return 0;
+
+    // var charLocation = new HashMap<Character, Integer>();
+
+    HashMap<Character, Integer> map = new HashMap();
+    int sum = 0;
+    for (int i = 0; i < s.length(); i++) {
+      map.putIfAbsent(s.charAt(i), i);
+    }
+    for (char key : map.keySet()) {
+      int indexInt = t.indexOf(Character.toString(key));
+      sum += Math.abs(s.indexOf(key) - indexInt);
+    }
+    return sum;
   }
 }