Quiz 01 sample questions

The quiz will have three questions.

In the first question, you will read some code and write a concise, high-level, English description of the code’s action. Here is an example:

double mystery(int[] a) {
  if (a.length == 0) {
    return 0.0;
  }

  double x = 0.0;
  for (int i: a) {
    x += i;
  }
  return x / a.length;
}

Here is another example:

int mystery(char c, String s) {
  int x = 0;
  for (char k : s.toCharArray()) {
    if (c != k) {
      x++;
    }
  }
  return x;
}

In the second question, you’ll identify a logic error in a short snippet of code. That is, you will find a conceptual error, not an error that the compiler would catch. Here is an example:

/** Return the mean of the values stored in `a`. */
double mean(int[] a) {
  if (a.length == 0) {
    return 0.0;
  }

  double x = 0.0;
  for (int i = 0; i < a.length; i++) {
    x += i;
  }
  return x / a.length;
}

Here is another example:

/** Return the sum of the odd numbers from 0 to n, inclusive. */
int sumOddUpTo(int n) {
  int sum = 0;
  for (int i = 0; i <= n; i++) {
    if (i % 2 == 0) {
      break;
    }
    else {
      sum += i;
    }
  }
  return sum;
}

In the final question, you will write a short class or method according to a textual description. For example, a question might state:

Define a class Dog. A Dog instance has a name (which could change), a breed (which is immutable, that is, it cannot change) and a licenseNumber (an integer between 1 and 1,000,000, which is immutable). Two Dog instances are considered equal if and only if their licenseNumbers are equal.

Your definition should include the constructor and the equals method, but should elide the getters and setters.

Another question might state:

Write a method which, given two int arrays, determines whether the values in the first array a are a subset of the values in the second array b. In other words, return true if and only if every value in a is also present in b. Your method should have the signature boolean isSubset(int[] a, int[] b).

You can check your answers here.