Udemy: Master Coding Interview - Stacks + Queues - #116

using System;

class Stack {
    int length = 0;
    string[] values;
    
    static void Main() {
        Console.WriteLine("Hello World!");
        
        Stack myStack = new Stack();
        Console.WriteLine("myStack: " + myStack.ToString());
        myStack.Push("Discord");
        Console.WriteLine("myStack: " + myStack.ToString());
        myStack.Push("Udemy");
        Console.WriteLine("myStack: " + myStack.ToString());
        myStack.Push("Google");
        Console.WriteLine("myStack: " + myStack.ToString());
        Console.WriteLine("myStack.Peek(): " + myStack.Peek());
        Console.WriteLine("myStack: " + myStack.ToString());
        myStack.Pop();
        Console.WriteLine("myStack: " + myStack.ToString());
        myStack.Pop();
        Console.WriteLine("myStack: " + myStack.ToString());
        myStack.Pop();
        Console.WriteLine("myStack: " + myStack.ToString());
    }
    
    public Stack() {
        this.values = new string[50];
    }
    
    public void Push(string value) {
        this.values[this.length] = value;
        this.length++;
    }
    
    public string Pop() {
        if (this.length > 0) {
            this.length--;
            return this.values[this.length];
        }
        return null;
    }
    
    public string Peek() {
        if (this.length > 0) {
            return this.values[this.length-1];
        }
        return null;
    }
    
    public string ToString() {
        string s = "{";
        int count = 0;
        for (int i = this.length-1; i >= 0; i--) {
            if (count > 0) {
                s += ", ";
            }
            count++;
            s += "" + this.values[i];
        }
        s += "}";
        return s;
    }
}