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..605e1b603 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
@@ -1,12 +1,18 @@
 package com.codedifferently.lesson13;
 
-public class Lesson13 {
+import java.util.HashMap;
 
-  /**
-   * Provide the solution to LeetCode 3146 here:
-   * https://leetcode.com/problems/permutation-difference-between-two-strings
-   */
+public class Lesson13 {
   public int findPermutationDifference(String s, String t) {
-    return 0;
+    var indexMap = new HashMap<Character, Integer>();
+    for (int i = 0; i < t.length(); i++) {
+      indexMap.put(t.charAt(i), i);
+    }
+
+    int result = 0;
+    for (int i = 0; i < s.length(); i++) {
+      result += Math.abs(i - indexMap.getOrDefault(s.charAt(i), -1));
+    }
+    return result;
   }
 }
diff --git a/lesson_13/maps_ts/src/lesson13.ts b/lesson_13/maps_ts/src/lesson13.ts
index 5207487e2..b0d483fdf 100644
--- a/lesson_13/maps_ts/src/lesson13.ts
+++ b/lesson_13/maps_ts/src/lesson13.ts
@@ -1,7 +1,14 @@
-/**
- * Provide the solution to LeetCode 3146 here:
- * https://leetcode.com/problems/permutation-difference-between-two-strings
- */
 export function findPermutationDifference(s: string, t: string): number {
-  return 0;
-}
+  const indexMap = new Map<string, number>();
+
+  for (let i = 0; i < t.length; i++) {
+    indexMap.set(t.charAt(i), i);
+  }
+
+  let result = 0;
+  for (let i = 0; i < s.length; i++) {
+    result += Math.abs(i - (indexMap.get(s.charAt(i)) ?? -1));
+  }
+
+  return result;
+}
\ No newline at end of file