feat: adds typescript implementation in lesson13.ts

Author: AmiyahJo

lesson_13/maps_ts/src/lesson13.ts

@@ -3,5 +3,22 @@
  * https://leetcode.com/problems/permutation-difference-between-two-strings
  */
 export function findPermutationDifference(s: string, t: string): number {
-  return 0;
+  //Create a way to find the index of each character in string s.
+  // This could be a list or a dictionary where each character points to its index in s.
+    let charPositionMap = new Map<string, number>();
+  //Start with a variable to keep track of the total permutation difference. Set it to 0.
+    let totalDifference = 0;
+  //For each character in t, find its index in s using the mapping you created.
+    for (let sIndex = 0; sIndex < s.length; sIndex++) {
+      charPositionMap.set(s.charAt(sIndex), sIndex)
+    }
+      
+    for (let tIndex = 0; tIndex < t.length; tIndex++) {
+  //Calculate the absolute difference between the index in s and the current index in t.
+      let indexInS = charPositionMap.get(t.charAt(tIndex));
+    //Add the absolute difference you calculated to the total difference.
+      totalDifference += Math.abs(indexInS - tIndex);
+    }
+  //After going through all characters in t, return the total difference.
+    return totalDifference;
 }