Day 17 / Mar 23 (Wed)¶

Warm-Up Exercises¶

Consecutive Duplicates of Elements¶

def consecutiveDuplicates[T](ts: Seq[T], n: Int): Seq[T]

val ns = Seq(1,2,3,4,5)
val actual = consecutiveDuplicates(ns, 3)
val expected = Seq(1,2,2,3,3,3,4,5,5)
assert(actual == expected)

val ss = Seq("one", "two", "three", "four")
val actual = consecutiveDuplicates(ns, 3)
val expected = Seq(
    "one",
    "two", "two",
    "three", "three", "three",
    "four")
assert(actual == expected)

Review a solution in solutions/consecutiveDuplicates.sc.

Pair Programming¶

File Stats using scopt¶

Use scopt to handle command-line options in the File Stats application we did yesterday:

1. --words - All the words and their occurences

2. --lines - All the lines and their length (number of characters, incl. whitespaces), the number of words, and the output of --words

Stacked Boxes¶

Develop an application that takes variable number of strings (of odd lenght, e.g. 1, 3, 5, ...) and prints them out as stacked boxes.

Solutions:

1. Adam + Rafał
2. Ania + Grzegorz + Janek
3. Daniel + Mateusz
4. Krzysiek + Damian

Scala Theory¶

1. Case classes and copy constructor

Exercises¶

1. Use Option[String] and boolean types to define options using scopt

From or based on Scala for the Impatient book:

1. sum(numbers) using foldLeft

2. Ex 5 page 26

   Write a procedure countdown(n: Int) that prints the numbers from n to 0.

3. Ex 2 page 38

   Write a loop that swaps adjancent elements of an array of integers.

   def swap[T](ts: Array[T]): Array[T]
   

   swap(Array(1,2,3,4,5)) == swap(Array(2,1,4,3,5))
   

4. Ex 9 page 47

   Write a function lteqgt(values: Array[Int], v: Int) that returns a triple containing the counts of values less than v, equal to v, and greater than v.

Schedule¶

1. 8:30 - 10:00
2. 10:15 - 12:00pm
3. 12:45pm - 1:15pm
4. 1:30pm - 2:30pm