EPAM Quest: Five Tasks from .NET Interviews

Before joining EPAM, I attended about 20 interviews in St. Petersburg IT companies, and many were given tasks. I synthesized my experience and came up with five tasks that are similar to those that give on online testing and face-to-face interviews.

On May 19-20, the DotNext conference was held in St. Petersburg, where we invited the participants to go through the quest, which consisted of these tasks. Answering the task correctly, the participant received the following.

The first three can be handled by juniors, they are often asked similar questions in interviews. You can ask the fourth one to anyone, but I would count on middle level specialists: not all juniors understand the increasing complexity of algorithms.

The fifth task was done by units. Its complexity is not in calculating what will happen in the select (many have dealt with it just that), but in finding the next number in the sequence, and this requires good mathematical knowledge. It seems to me that the mathematical base is very important for the programmer.

Conference participants came up and asked how to solve problems and where you can see their complete list, and I promised that I would publish them here. The correct answers and comments are hidden so that those who see the tasks for the first time can solve them without prompting.

So, let's begin.

1) What result will this program print to the console?

    class Program
    {
        static void Main(string[] args)
        {
            var numbers = new int[] { 7, 2, 5, 5, 7, 6, 7 };
            var result = numbers.Sum() + numbers.Skip(2).Take(3).Sum();
            var y = numbers.GroupBy(x => x).Select(x =>
            {
                result += x.Key;
                return x.Key;
            });
            Console.WriteLine(result);
        }
    }

2) What result will this program print to the console?

    class Program
    {
        private static string GetNumber(int input)
        {
            try
            {
                throw new Exception(input.ToString());
            }
            catch (Exception e)
            {
                throw new Exception((int.Parse(e.Message) + 3).ToString());
            }
            finally
            {
                throw new Exception((++input).ToString());
            }
            return (input += 4).ToString();
        }
        static void Main(string[] args)
        {
            string result;
            try
            {
                result = GetNumber(1);
            }
            catch (Exception e)
            {
                result = e.Message;
            }
            Console.WriteLine(int.Parse(result) * 100);
        }
    }

3) What result will this program print to the console?

    class MagicValue
    {
        public int Left { get; set; }
        public int Right { get; set; }
        public MagicValue(int left, int right)
        {
            Left = left;
            Right = right;
        }
        public static void Apply(MagicValue magicValue)
        {
            magicValue.Left += 3;
            magicValue.Right += 4;
            magicValue = new MagicValue(5, 6);
        }
        public static void ApplyRef(ref MagicValue magicValue)
        {
            magicValue.Left += 7;
            magicValue.Right += 8;
            magicValue = new MagicValue(9, 10);
        }
    }
    class Program
    {
        static void Main(string[] args)
        {
            var magicValue = new MagicValue(1, 2);
            MagicValue.ApplyRef(ref magicValue);
            MagicValue.Apply(magicValue);
            Console.WriteLine(magicValue.Left * magicValue.Right);
        }
    }

4) Given 9 functions. Each function corresponds to a number from 1 to 9. Arrange the functions in order of increasing complexity, and then substitute 9 numbers of sorted functions sequentially in the formula _ _ _ - _ _ _ + _ _ _ = "?". Write what "?" Is equal to.

1.$$
2. $$
3. $$
4. $$
5. $$
6. $$
7. $$
8. $$
9. $$



5) Let the carTable table contain the following values:

id	model	price
1	Nissan	1000
2	BMW	2000
3	Toyota	1000
4	Renault	2000
5	Peugeot	1000
6	Opel	2000

The result of the SQL query below will be 2 values ​​- <1> and <2>.

;WITH someTable AS
(SELECT 1 val
UNION ALL
SELECT val + 1 FROM someTable WHERE val BETWEEN 1 AND 3)
SELECT carTable.price / SUM(CASE WHEN carTable.price = 1000 THEN 1 ELSE 2 END) / 250 AS result
FROM someTable
INNER JOIN carTable ON carTable.id = someTable.val
GROUP BY carTable.price
ORDER BY carTable.price ASC

<1> and <2> - is a first sequence number <1>, <2>, 6, 34, 270 .
Find the following sequence number.

Conclusion

Thanks to everyone who solved the problems, and especially to those who managed to get to the end! It was interesting to read your reviews and comments. And those who carefully read the conditions and gave answers in binary form are doubly well done!

Photo taken from the archive of the DotNext conference.