Monobilliard

using System;
using System.Collections.Generic;

namespace Monobilliards
{
    public class Monobilliards : IMonobilliards
    {
        public bool IsCheater(IList<int> inspectedBalls)
        {
            var stack = new Stack<int>();
            var queue = new Queue<int>();

            foreach (var ball in inspectedBalls)
                queue.Enqueue(ball);

            for (int i = 1; i < inspectedBalls.Count+1; i++)
            {
                stack.Push(i);
                while (stack.Peek() == queue.Peek())
                {
                    stack.Pop();
                    queue.Dequeue();
                    if ((stack.Count == 0) || (queue.Count == 0))
                        break;
                }
            }
            return (stack.Count != 0);
        }
    }
}