CyberChallenge.IT 2018

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CyberChallenge.IT 2018 - Pretest

Demo of the pretest for the 2018 edition of CyberChallenge.IT

Additional material for other tests is available at the link https://cyberchallenge.it/training

Question 1

Function search is supposed to return 1 if x belongs to an ordered array v of size n, and 0 otherwise:

What would you put in place of ...?

1 point

b+1

(b-1)/2

a-1

(a+b)/2

Clear selection

Question 2

What does int (*x[10])(); mean in C?

1 point

x is a pointer to an array of 10 functions without arguments that return int

x is a function without arguments that returns and array of 10 pointers to int

x is an array of 10 pointers to functions without arguments that return int

x is an array of 10 functions that return a pointer to int

Clear selection

Question 3

Consider the following function:

What does this C function do?

Assume that sizeof(int) is 4.

1 point

computes a checksum of all bytes of array v

rotates the content of array v

the code is wrong

reverses the content of array v

Clear selection

Question 4

Consider the following C function:

Which of the following is correct?

1 point

The program is correct

There is an error at line 1

There is an error at line 3

There is an error at line 4

There is an error at line 2

Clear selection

Question 5

Let int x, y be two integers that represent Boolean values (zero means false, and a non-zero value means true).

How would you check in C that x is true if and only if y is true?

1 point

(x && !y) || (y && !x)

(x == y) || !x && !y

(x || !y) && (y || !x)

(!x == !y) && !x || !y

Clear selection

Question 6

During a recruitment interview, you are asked to write your own version of the standard strlen function:

Would you put in place of ...?

1 point

while (s[cnt]) { s++; cnt++; }

while (s[cnt++]);

while (*s++) cnt++;

do { cnt++; s++; } while(*s != ’\0’);

Clear selection

Question 7

Consider the two C expressions x & 255 and x % 256.

Which of the following is correct?

1 point

the two expressions are always interchangeable regardless of the type of x

the two expressions are never interchangeable unless x is a floating-point variable

the two expressions are always interchangeable if x is an unsigned integral variable

the two expressions are never interchangeable

Clear selection

Question 8

Let y be a double in C and let x = (long)(y + 0.5).

Which of the following is correct?

1 point

x is obtained by rounding y to the nearest integer

x-y is always equal to 0.5

x is the largest integer smaller than y

x is the smallest integer larger than y

x is equal to y if and only if y-0.5 is integral

Clear selection

Question 9

Consider the following two C functions:

Which of the following is correct?

1 point

foo and bar are always interchangeable

foo and bar are never interchangeable

foo and bar are interchangeable only if x does not belong to v

foo and bar are interchangeable only if n is non-zero

Clear selection

Question 10

The following function is supposed to compute the sum of all even numbers up to n if n is even, and the sum of all odd numbers up to n if n is odd:

Which of the following is correct?

1 point

the function never returns the expected value

the function works correctly only if n is even

the function works correctly only if n is odd

the function always returns the expected value

Clear selection

Question 11

If you write down all the numbers from 300 to 400, how many times do you have to write the digit 3?

1 point

120

109

100

110

Clear selection

Question 12

There are 27 tennis balls. 26 of them have the same weight and the twenty-seventh is a bit heavier.

In the worst case scenario, what is the minimum number of weighings you need to identify the heavy one by using a two-pan balance scale?

1 point

Clear selection

Question 13

Pedro is a contestant on a “Deal or No Deal” game, and he’s given the choice of three boxes: inside one box is a one million prize, while the others are empty. He picks a box, say No. 1, and the host, who knows what’s inside the boxes, opens another box, say No. 3, which is empty. He then asks him, ”Do you want to pick box No. 2 instead?”

Is it to his advantage to switch his choice?

1 point

it's the same

it's the onion

yes

Clear selection

Question 14

A director wishes to know how many times their movie has been shown in a given theater. The theater’s staff provides the following info:

- at the first projection there’s just 1 viewer;

- at each projection, the number of viewers grows by 1 compared to the previous one;

- 820 tickets are sold over all the projections.

How many projections were held?

1 point

Clear selection

Question 15

You can paddle your canoe 7 miles per hour through any placid lake. You’re paddling through the Wabash river and the stream constantly flows at 3 miles per hour. The moment you start to paddle up stream, a fisherman looses one of his fishing bobbers in the water 14 miles up stream of you.

How many hours does it take for you to reach the bobber?

1 point

1.5

2.5

Clear selection

Submit

Clear form

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