fix: lesson13.ts variables changed from let to const

Author: AmiyahJo

lesson_13/maps_ts/src/lesson13.ts

@@ -1,5 +1,5 @@
 export function findPermutationDifference(s: string, t: string): number {
-    let charPositionMap = new Map<string, number>();
+    const charPositionMap = new Map<string, number>();
 
     let totalDifference = 0;
 
@@ -8,7 +8,7 @@ export function findPermutationDifference(s: string, t: string): number {
     }
 
     for (let tIndex = 0; tIndex < t.length; tIndex++) {
-      let indexInS = charPositionMap.get(t.charAt(tIndex));
+      const indexInS = charPositionMap.get(t.charAt(tIndex));
 
       if (indexInS != undefined) {
         totalDifference += Math.abs(indexInS - tIndex);