lesson_13_homework

Author: jxwatson251

lesson_13/maps_java/maps_app/package-lock.json

@@ -1,12 +1,35 @@
 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;
+    int difference = 0;
+
+    var charByIndex = new HashMap<Character, Integer>();
+
+    for (int i = 0; i < s.length(); i++) {
+      charByIndex.put(s.charAt(i), i);
+    }
+
+    for (int j = 0; j < t.length(); j++) {
+      char ch = t.charAt(j);
+
+      if (charByIndex.containsKey(ch)) {
+
+        difference += Math.abs(charByIndex.get(ch) - j);
+      } else {
+
+        int indexInS = s.indexOf(ch);
+        difference += Math.abs(indexInS - j);
+      }
+    }
+
+    return difference;
   }
 }

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

@@ -3,5 +3,18 @@
  * https://leetcode.com/problems/permutation-difference-between-two-strings
  */
 export function findPermutationDifference(s: string, t: string): number {
-  return 0;
+  const charByIndex = new Map<string, number>();
+  let difference = 0;
+
+  for (let i = 0; i < s.length; ++i) {
+    charByIndex.set(s[i], i);
+  }
+
+  for (let j = 0; j < t.length; ++j) {
+    if (charByIndex.has(t[j])) {
+
+      difference += Math.abs(charByIndex.get(t[j]) as number - j);
+    }
+  }
+  return difference;
 }