C# list STACK OPASHKA

//  list<T>  ////////////


int[] arr1 = {1,2,3,4,5,6,7};
            int[] arr2 = {2,3,4,5,6,7,8};

            int[] kur = new int[0];
            kur = Union(arr1, arr2);

            for (int i = 0; i < 8; i++)
            {
                Console.WriteLine(kur[i] + " ");
            }
        }
         public static int[] Union(int[] firstarr, int[] secondarr)
        {
            List<int> union = new List<int>();

            union.AddRange(firstarr);

            foreach (var item in secondarr)
            {
                 if (! union.Contains(item))
              {
                  union.Add(item);
              }
            }
            return union.ToArray();
        }



///////// 2 primer vzima samo suvpadashtite 4isla ot 2ta masiva ///////////////////


  static void Main(string[] args)
        {

            int[] arr1 = {2,3,4,5,6,9};
            int[] arr2 = {7,8,2,5};

            int[] kur = new int[0];
            kur = Inter(arr1, arr2);

            for (int i = 0; i < 22; i++)
            {
                Console.WriteLine(kur[i] + " ");
            }

        }
         public static int[] Inter(int[] firstarr, int[] secondarr)
        {
            List<int> union = new List<int>();

            foreach (var item in firstarr)
            {
                 if (Array.IndexOf(secondarr, item) != -1)
              {
                  union.Add(item);
              }
            }

            return union.ToArray();
        }



////////////// stack  primer sus stek  ////////////////////////////////////////////


 Stack<string> stek = new Stack<string>();

            stek.Push("1. ivan");
            stek.Push("2. divan");
            stek.Push("3. many");
            stek.Push("4. floyd");
            stek.Push("5. kondio");

            Console.WriteLine("top = {0}", stek.Peek());

            while (stek.Count > 0)
            {
                string name = stek.Pop();
                Console.WriteLine(name);
            }


//////////////////// stack primer brackets  /////////////////////////////////


 string expr = "1 + (2 - (2+3) * 4 / (3+1)) + 5";

            Stack<int> stek = new Stack<int>();

            for (int i = 0; i < expr.Length; i++)
            {
                char ch = expr[i];
                if (ch == '(')
                {
                    stek.Push(i);
                }
                else if (ch == ')')
                {
                    int startIndex = stek.Pop();
                    int length = i - startIndex + 1;
                    string contents = expr.Substring(startIndex, length);
                    Console.WriteLine(contents);
                }
             }


////////////////////////////////// stack  primer s start i end index  ///////////////////////////////////////


            int[] array = { 2, 3, -6, -1, 2, -1, 6, 4, -8, 8 };// ako si sloja 9 she mi zeme do 9
            Stack<int> stek = new Stack<int>();
            int currentSum = array[0];
            int startIndex = 0;
            int endIndex = 0;

            int maxSum = array[0];
            int count = 0;

            for (int i = 1; i < array.Length; i++)
            {
                if (currentSum < 0)
                {
                    currentSum = array[i];
                    stek.Push(i);
                }
                else
                {
                    currentSum += array[i];
                    count++;
                }

                if (i != 1)
                {
                     if (currentSum > maxSum)
                {
                    maxSum = currentSum;

                        startIndex = stek.Pop() + 1;

                        endIndex =  (i+1) - count +  startIndex;
                }
                }

            }

            Console.WriteLine("The best sum is: {0} ", maxSum);

            Console.WriteLine("The best sequence is:");

            for (int i = startIndex; i <= endIndex; i++)
            {
                Console.Write(i != endIndex ? array[i] + ", " : array[i] + "\n");
            }
            Console.WriteLine();






///////////////////////  queue  opashka primer ///////////////////////////////////////////////

 Queue<string> opshka = new Queue<string>();

            opshka.Enqueue("1 kondio");
            opshka.Enqueue("2 ondio");
            opshka.Enqueue("3 ndio");
            opshka.Enqueue("4 dio");
            opshka.Enqueue("5 io");

            while (opshka.Count > 0)
            {
                string mas = opshka.Dequeue();
                Console.WriteLine(mas);
            }


/////////////////////  opshka  primer s 4isla  ///////////////////

            int n = 3;
            int p = 16;

            Queue<int> opshka = new Queue<int>();

            opshka.Enqueue(n);

            int index = 0;
            while (opshka.Count > 0)
            {
                int current = opshka.Dequeue();
                index++;
                if (current == p)
                {
                    Console.WriteLine("Index = {0}", index);
                }

                opshka.Enqueue(current + 1);
                opshka.Enqueue(2 * current);
            }



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