feat: adds amiyah jones' lesson 12 & stack typescript files

lesson_12/structs_ts/src/lesson12.ts

@@ -1,11 +1,26 @@
 import { ListNode } from './list_node.js';
 
 export class Lesson12 {
-  /**
-   * Provide the solution to LeetCode 3062 here:
-   * https://github.com/yang-su2000/Leetcode-algorithm-practice/tree/master/3062-winner-of-the-linked-list-game
-   */
+
   public gameResult(head: ListNode | null): string {
-    return '';
+    let [oddPoints, evenPoints] = [0,0];
+    let current = head;
+
+   while (current != null && current.next != null) {
+      if (current.val > current.next.val) {
+        evenPoints++;
+      } else if (current.val < current.next.val) {
+        oddPoints++;
+      }
+      current = current.next ? current.next.next || null : null; 
+    }
+
+    if (oddPoints > evenPoints) {
+      return 'Odd';
+    } else if (evenPoints > oddPoints) {
+      return 'Even';
+    } else {
+      return 'Tie';
+    }
   }
 }

lesson_12/structs_ts/src/stack.ts

@@ -8,18 +8,29 @@ export class Stack {
   }
 
   push(value: number): void {
-    throw new Error('Not implemented');
+    const newNode = new ListNode(value)
+    newNode.next = this.top;
+    this.top = newNode;
   }
 
   pop(): number | undefined {
-    throw new Error('Not implemented');
+    if (this.isEmpty()) {
+      return undefined;
+    }
+
+    const value = this.top?.val;
+    this.top = this.top?.next;
+    return value;
   }
 
   peek(): number | null {
-    throw new Error('Not implemented');
+    if (this.top === undefined) {
+      throw new Error('Stack is empty');
+    } 
+    return this.top.val;
   }
 
   isEmpty(): boolean {
-    throw new Error('Not implemented');
+    return this.top === undefined;
   }
 }