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 0c981abbf..c706fbb1d 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
@@ -7,6 +7,17 @@ public class Lesson13 {
    * https://leetcode.com/problems/permutation-difference-between-two-strings
    */
   public int findPermutationDifference(String s, String t) {
-    return 0;
+    int ans = 0;
+    int[] indices = new int[26];
+
+    for (int i = 0; i < s.length(); ++i) {
+      indices[s.charAt(i) - 'a'] = i;
+    }
+
+    for (int i = 0; i < t.length(); ++i) {
+      ans += Math.abs(indices[t.charAt(i) - 'a'] - i);
+    }
+
+    return ans;
   }
 }
diff --git a/lesson_13/maps_ts/src/lesson13.ts b/lesson_13/maps_ts/src/lesson13.ts
index 5207487e2..ee3a0d8fc 100644
--- a/lesson_13/maps_ts/src/lesson13.ts
+++ b/lesson_13/maps_ts/src/lesson13.ts
@@ -3,5 +3,15 @@
  * https://leetcode.com/problems/permutation-difference-between-two-strings
  */
 export function findPermutationDifference(s: string, t: string): number {
-  return 0;
+  let ans: number = 0;
+let indices: number[] = new Array(26).fill(0);
+
+for (let i = 0; i < s.length; ++i){
+  indices[s.charCodeAt(i) - 'a'.charCodeAt(0)] = i;
+}
+
+for (let i = 0; i < t.length; ++i){
+  ans += Math.abs(indices[t.charCodeAt(i) - 'a'.charCodeAt(0)] - i);
+}
+return ans;
 }