Quest from EPAM: Five Tasks from .NET Interviews

Before I came to EPAM, I visited about 20 interviews at 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 are given on online testing and face-to-face interviews.

On May 19-20, a DotNext conference was held in St. Petersburg, where we invited participants to complete a quest, which consisted of these tasks. Responding correctly to the task, the participant received the following.
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Juniors can cope with the first three, they are often asked similar questions at interviews. The fourth one can be set to anyone, but I would count on middle-level specialists: not all juniors understand the increasing complexity of algorithms.

The fifth task handled units. Its complexity is not to calculate what will be in the select (many have coped with it), but to find the next number in the sequence, and this requires good mathematical knowledge. It seems to me that the mathematical base is very important for a programmer.

The conference participants approached and asked how to solve problems and where to see their complete list, and I promised that I would post them here. The correct answers and comments are hidden so that those who see the tasks for the first time can solve them without prompts.

So, let's begin.

1) What result will this program display on 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 display on 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 display on 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, then substitute 9 numbers of sorted functions sequentially in the _ _ _ _ _ _ _ + _ _ = = formula? Write what "?" Equals.

one. $$$log⁡ (log (N))$
2 $$$N ^ {2/9}$
3 $$$log (N)$
four. $$$N$
five. $$$3 ^ n$
6 $$$900 ^ {10,000,000}$
7 $$$N!$
eight. $$$N ^ 3$
9. $$$N * log (N)$



5) Let the carTable table contain the following values:

id	model	price
one	Nissan	1000
2	BMW	2000
3	Toyota	1000
four	Renault	2000
five	Peugeot	1000
6	Opel	2000

The result of the SQL query below is 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> are the first numbers of the sequence <1>, <2>, 6, 34, 270, <?>.
Find the next sequence number.

Conclusion

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

Photo taken from the archives of the conference DotNext.