feat: add explicit return types to functions in mergeSortCounters and BinaryTree classes; update ESLint configuration for function return type enforcement

Author: monkey0722

algorithms/sorting/merge-sort-counters/mergeSortCounters.ts

@@ -7,7 +7,7 @@ let countOuter = 0;
 let countInner = 0;
 let countSwap = 0;
 
-function resetCounters() {
+function resetCounters(): void {
   countOuter = 0;
   countInner = 0;
   countSwap = 0;

data-structures/binary-tree/binaryTree.ts

@@ -10,7 +10,7 @@ export class BinaryTree<T> {
    * Inserts a new value into the binary search tree.
    * @param {T} value The value to insert.
    */
-  insert(value: T) {
+  insert(value: T): void {
     const newNode = new BinaryTreeNode(value);
     if (this.root === null) {
       this.root = newNode;
@@ -19,7 +19,10 @@ export class BinaryTree<T> {
     }
   }
 
-  private insertNode(node: BinaryTreeNode<T>, newNode: BinaryTreeNode<T>) {
+  private insertNode(
+    node: BinaryTreeNode<T>,
+    newNode: BinaryTreeNode<T>
+  ): void {
     if (newNode.value < node.value) {
       if (node.left === null) {
         node.left = newNode;
@@ -65,8 +68,8 @@ export class BinaryTree<T> {
    * Traverses the binary search tree in order (left, root, right).
    * @param {function} visit Function to call on each value.
    */
-  inOrderTraverse(visit: (value: T) => void) {
-    function traverse(node: BinaryTreeNode<T> | null) {
+  inOrderTraverse(visit: (value: T) => void): void {
+    function traverse(node: BinaryTreeNode<T> | null): void {
       if (node === null) return;
       traverse(node.left);
       visit(node.value);
@@ -79,7 +82,7 @@ export class BinaryTree<T> {
    * Removes a value from the binary search tree.
    * @param {T} value The value to remove.
    */
-  remove(value: T) {
+  remove(value: T): void {
     this.root = this.removeNode(this.root, value);
   }
 

eslint.config.js

@@ -20,6 +20,10 @@ module.exports = [
       "no-irregular-whitespace": ["error", { skipTemplates: true }],
       "@typescript-eslint/no-unused-vars": "error",
       "@typescript-eslint/no-useless-constructor": "error",
+      "@typescript-eslint/explicit-function-return-type": ["warn", {
+        allowExpressions: true,
+        allowTypedFunctionExpressions: true,
+      }],
       "@typescript-eslint/no-floating-promises": "error",
       "@typescript-eslint/await-thenable": "error",
       "eqeqeq": ["error", "always", { null: "ignore" }],