Below please find links to archived Q&A discussion for the Data Structures course.
Exercise 1.1: Creating ArraysExercise 1.2: Access by IndexExercise 1.3: Arrays of Non-NumbersExercise 1.4: Arrays of ArraysExercise 1.5: Create Your Own
Exercise 2.1: Introduction to HashesExercise 2.2: Using Hash.newExercise 2.3: Adding to a HashExercise 2.4: Accessing Hash Values
Exercise 3.1: (Re)Introduction to IterationExercise 3.2: Iterating Over ArraysExercise 3.3: Iterating Over Multidimensional ArraysExercise 3.4: Iterating Over Hashes
Exercise 4.1: Multidimensional ArraysExercise 4.2: HashesExercise 4.3: Iterating Over a Hash