Implemented array-based Stack (Closes CoffeelessProgrammer#3)

Implemented array style Stack. Added getLength() method to Stack data structures.

Author: CoffeelessProgrammer

Data-Structures/Sequential/Stack.ts

@@ -0,0 +1,76 @@
+export default class Stack<T> {
+  private length: number;
+  private values: Array<T>;
+
+  constructor() {
+    this.length = 0;
+    this.values = new Array<T>();
+  }
+
+  public getLength(): number {
+    return this.length;
+  }
+
+  public peek(): T | null {
+    return this.values[this.length-1] || null;
+  }
+
+  public push(value: T): boolean {
+    this.values[this.length] = value;
+    ++this.length;
+    return true;
+  }
+
+  public pop() {
+    const value = this.values[this.length-1];
+    delete this.values[this.length-1];
+    --this.length;
+    return value;
+  }
+}
+
+function printStack(stack: Stack<any>) {
+  console.log(JSON.stringify(stack));
+}
+
+function printPopStack(stack: Stack<any>) {
+  console.log('Popped:', stack.pop());
+}
+
+function printPeekStack(stack: Stack<any>) {
+  console.log('Peeking... Found', stack.peek());
+}
+
+//---------------------------------------------------------------------
+// ----------                 MAIN PROGRAM                   ----------
+//---------------------------------------------------------------------
+if (import.meta.main) {
+
+  const ATLA = new Stack<string>();
+
+  printPeekStack(ATLA);
+  ATLA.push('Sokka');
+  ATLA.push('Katara');
+  printPeekStack(ATLA);
+  ATLA.push('Aang');
+  ATLA.push('Appa');
+
+  printStack(ATLA);
+
+  printPopStack(ATLA);
+
+  printStack(ATLA);
+
+  printPopStack(ATLA);
+  printPopStack(ATLA);
+  printPopStack(ATLA);
+
+  printStack(ATLA);
+  
+  ATLA.push('Zuko');
+  ATLA.push('Iroh');
+
+  printStack(ATLA);
+
+  // RUN: deno run Data-Structures/Sequential/Stack.ts
+}

Data-Structures/Sequential/StackLL.ts

@@ -12,6 +12,10 @@ export default class StackLL<T> {
     this.length = 0;
   }
 
+  public getLength(): number {
+    return this.length;
+  }
+
   public peek(): T | null {
     return this.top?.getValue() || null;
   }
@@ -50,7 +54,7 @@ export default class StackLL<T> {
     const value = this.top.getValue();    // Retrieve top value of stack
     this.top = this.top.getNext();        // Move top pointer to next node
 
-    // On line 46, the reference to the top most node of the stack is lost
+    // On line 55, the reference to the top most node of the stack is lost
     // The node is now floating in memory, waiting patiently for the garbage collector
 
     --this.length;