feat: lesson_13 solution implementation by Tommy Tran

Author: txtran224

lesson_13/maps_java/maps_app/src/main/java/com/codedifferently/lesson13/Lesson13.java

@@ -1,12 +1,28 @@
 package com.codedifferently.lesson13;
 
+import java.util.HashMap;
+
 public class Lesson13 {
 
   /**
    * Provide the solution to LeetCode 3146 here:
    * https://leetcode.com/problems/permutation-difference-between-two-strings
    */
   public int findPermutationDifference(String s, String t) {
-    return 0;
+HashMap<Character,Integer> smap = new HashMap<>();
+HashMap<Character,Integer> tmap = new HashMap<>();
+int sum = 0;
+  for (int i =0; i <s.length(); i++){
+    smap.put(s.charAt(i),i);
+    tmap.put(t.charAt(i),i);
+  }
+  for (Character key:smap.keySet()){
+    if (tmap.containsKey(key)) {
+      Integer val1 = smap.get(key);
+      Integer val2 = tmap.get(key);
+      sum += Math.abs(val1-val2);
+            }
+        }
+        return sum;
   }
 }