Practice with Collections

Created By: Geoffrey Challen

/ Version: 2022.2.0

Write a method called sectionListsToMap that, given a List of Strings, parses it into a Map<String, MutableSet<String>> as follows. Each String in the passed list contains a comma-separated list of names of people in a discussion section. The first name is the section leader, and the rest are students. Your map should map each section leader to the set of students in their section. No section leader or student will appear twice in the data set.

For example, given the Strings "challen,student1", "ruisong4,student2, student3" and "friendly,student4, student5", your map would have keys "challen", "ruisong4", and "friendly". "challen" would map to a set containing "student1", "ruisong4" would map to a set containing "student2" and "student3", and so on.

A few hints for approaching this problem. First, consider how to use .split and .trim appropriately to parse the input String. You should get this part to work before proceeding. Then consider when you need to create the map and each set, and how to populate them.

You should not need import statements to solve this problem. Rather, create your maps and sets using mutableMapOf() and mutableSetOf() where appropriate.

Homework: Hawaiian Words

Created By: Geoffrey Challen

/ Version: 2022.7.0

Words from languages that we are unfamiliar with can be difficult to pronounce correctly. Phonetic pronunciation guides can help make them more accessible to us. For this problem, you will write a program that produces phonetic pronunciations for Hawaiian words.

Write a method getPronunciation that accepts a single non-null String containing a potential Hawaiian word and returns a String containing the pronunciation guide. If the passed is invalid, throw an IllegalArgumentException.

Hawaiian Characters

There are 12 valid characters in the Hawaiian language: a, e, i, o, u, p, k, h, l, m, n, and w. Each Hawaiian word passed into our program must be inspected to ensure it contains only these characters, because if it does not, then we don’t have a valid Hawaiian word. If the passed word is not valid, throw an IllegalArgumentException. Note that you do not need to handle spaces or any other characters. You should ignore case when examining the input String, but your pronunciation guide output String should be all lowercase.

The consonants in the Hawaiian language are pronounced similarly to the English versions. The only exception is 'w', which is pronounced as a "v" if it follows an 'i' or 'e' and pronounced as "w" otherwise.

The vowels in the Hawaiian language are a, e, i, o, and u:

• 'a' sounds like "ah" like "aha"
• 'e' sounds like "eh" like "egg"
• 'i' sounds like "ee" like "bee"
• 'o' sounds like "oh" like "obey"
• 'u' sounds like "oo" like "mood"

Vowel groups are also present in the Hawaiian language. More complex words can have many vowels that when grouped together require additional rules. This means we can't simply replace all 'a's with "ah", and so on.

We will consider the following simplification of the Hawaiian vowel groups for this problem:

• "ai" and "ae" sound like "eye"
• "ao" and "au" sound like "ow"
• "ei" sounds like "ay"
• "eu" sounds like "eh-oo"
• "iu" sounds like "ew"
• "oi" sounds like "oy"
• "ou" sounds like "ow"
• "ui" sounds like "ooey"

Examples

Here are a few examples used by the test suite:

• aloha: ah-loh-hah
• keikikane: kay-kee-kah-neh
• iwa: ee-vah
• MaHALO: mah-hah-loh

Note that the testing process will start by testing "w", then move on to single vowels, then test vowel groups, and then proceed to more complicated inputs, some of which will be invalid. So you can design your solution incrementally following the progression of the test suites.

Hints

A few hints to help you get started.

One way to proceed is to examine each character in the input String and build up the pronunciation guide from an empty String as you go. However, for this to work, some rules need access to the previous character (like 'w') and others to the next character (vowel groups), so it may be helpful to record the current character as well as the previous and next characters inside your loop. Doing this safely requires some care, given that the previous and next character are not always valid depending on where you are in the String.

Usually you'll want to consume one character at a time. But when you find a vowel group, you'll need to make sure you skip the next character. For example, given the input "ai", you'll need to make sure you output only "eye" and not "eye-ee" or "ah-ee".

Finally, take care to insert dashes in the correct places. A pronunciation should never end in a dash. You can avoid this by keeping track of where you are inside the loop, but it may be simpler to simply detect if your pronunciation ends with a dash and remove it before returning.