exercise-09

using System;
using System.Collections.Generic; // for the List<int> fiveNumbers

class SumOfSubset
{
    static void Main()
    {
        /* We are given 5 integer numbers. Write a program that checks if the sum of some subset of them is 0.
         * Example: 3, -2, 1, 1, 8  1+1-2=0.
         */

        Console.Write("integer 1: ");
        int first = int.Parse(Console.ReadLine());
        Console.Write("integer 2: ");
        int second = int.Parse(Console.ReadLine());
        Console.Write("integer 3: ");
        int third = int.Parse(Console.ReadLine());
        Console.Write("integer 4: ");
        int fourth = int.Parse(Console.ReadLine());
        Console.Write("integer 5: ");
        int fifth = int.Parse(Console.ReadLine());
        Console.WriteLine();

        List<int> fiveNumbers = new List<int> { first, second, third, fourth, fifth }; // list with the five integers
        int sumCounter = 0; // the number of subsets with sum = 0

        for (int i = 0; i < fiveNumbers.Count-1; i++) // number + next to it == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 1] == 0)
            {
                Console.WriteLine("{0} + {1} = 0", fiveNumbers[i], fiveNumbers[i + 1]);
                sumCounter++;
            }
        }

        for (int i = 0; i < fiveNumbers.Count-2; i++) // number + next + next == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 1] + fiveNumbers[i + 2] == 0)
            {
                Console.WriteLine("{0} + {1} + {2} = 0", fiveNumbers[i], fiveNumbers[i + 1], fiveNumbers[i + 2]);
                sumCounter++;
            }
        }

        for (int i = 0; i < fiveNumbers.Count-3; i++) // number + next + next + next == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 1] + fiveNumbers[i + 2] + fiveNumbers[i + 3] == 0)
            {
                Console.WriteLine("{0} + {1} + {2} + {3} = 0", fiveNumbers[i], fiveNumbers[i + 1], fiveNumbers[i + 2], fiveNumbers[i + 3]);
                sumCounter++;
            }
        }

        for (int i = 0; i < fiveNumbers.Count - 2; i++) // number + number through 1 == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 2] == 0)
            {
                Console.WriteLine("{0} + {1} = 0", fiveNumbers[i], fiveNumbers[i + 2]);
                sumCounter++;
            }
        }

        for (int i = 0; i < fiveNumbers.Count - 3; i++) // number + number through 2 == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 3] == 0)
            {
                Console.WriteLine("{0} + {1} = 0", fiveNumbers[i], fiveNumbers[i + 3]);
                sumCounter++;
            }
        }

        for (int i = 0; i < fiveNumbers.Count - 4; i++) // number + number through 3 == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 4] == 0)
            {
                Console.WriteLine("{0} + {1} = 0", fiveNumbers[i], fiveNumbers[i + 4]);
                sumCounter++;
            }
        }

        for (int i = 0; i < fiveNumbers.Count - 4; i++) // number + number through 1 + number through 1 == 0
        {
            if (fiveNumbers[i] + fiveNumbers[i + 2] + fiveNumbers[i + 4] == 0)
            {
                Console.WriteLine("{0} + {1} + {2} = 0", fiveNumbers[i], fiveNumbers[i+2], fiveNumbers[i + 4]);
                sumCounter++;
            }
        }

        if (sumCounter == 0) // check how many subsets with sum = 0 there are
        {
            Console.WriteLine();
            Console.WriteLine("There are no subsets with sum = 0.");
        }
        else
        {
            Console.WriteLine();
            Console.WriteLine("Total subsets with sum = 0 are: {0}",sumCounter );
        }
        Console.WriteLine();

    }
}