Stack

Last-in, first-out (LIFO). Good for undo operations, parsing expressions, or tracking function calls.

class Stack {
  private items: number[];

  constructor() {
    this.items = [];
  }

  // Add an element to the top
  push(item: number): void {
    this.items.push(item);
  }

  // Remove and return the top element
  pop(): number | undefined {
    return this.items.pop();
  }

  // Return the top element without removing it
  peek(): number | undefined {
    return this.items[this.items.length - 1];
  }
}

const stack = new Stack();
stack.push(1);
stack.push(2);
console.log(stack.peek()); // Output: 2
console.log(stack.pop()); // Output: 2
console.log(stack.pop()); // Output: 1
console.log(stack.pop()); // Output: undefined

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