Solution4.cs

using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace cSharpSolutions
{
    internal class Solution4
    {
        private class CircularQueue<T>
        {
            private T[] items;
            private int head, tail, count, capacity;

            public CircularQueue(int capacity = 4)
            {
                this.capacity = capacity;
                items = new T[capacity];
                head = tail = count = 0;
            }

            public void Enqueue(T item)
            {
                if (count == capacity) Resize(capacity * 2);
                items[tail] = item;
                tail = (tail + 1) % capacity;
                count++;
            }

            public T Dequeue()
            {
                if (IsEmpty()) throw new InvalidOperationException("Queue is empty.");
                T value = items[head];
                head = (head + 1) % capacity;
                count--;
                return value;
            }

            public T Peek()
            {
                if (IsEmpty()) throw new InvalidOperationException("Queue is empty.");
                return items[head];
            }

            public bool IsEmpty() => count == 0;
            public int Count() => count;

            private void Resize(int newCapacity)
            {
                T[] newArr = new T[newCapacity];
                for (int i = 0; i < count; i++)
                    newArr[i] = items[(head + i) % capacity];
                items = newArr;
                head = 0;
                tail = count;
                capacity = newCapacity;
            }
        }

        public static void Run()
        {
            Console.WriteLine("=== Solution 4: Circular Queue ===");

            var queue = new CircularQueue<int>();
            queue.Enqueue(1);
            queue.Enqueue(2);
            queue.Enqueue(3);

            Console.WriteLine($"Queue count: {queue.Count()}, front: {queue.Peek()}");

            Console.WriteLine("Dequeueing elements:");
            while (!queue.IsEmpty())
                Console.WriteLine(queue.Dequeue());

            Console.WriteLine($"Queue empty? {queue.IsEmpty()}");

            Console.WriteLine("\nSolution 4 complete");
        }
    }
}