Longest_Word_in_String.swift

/*:
 # Tuesday Stretch Problem 5.2
 ## Longest Word In String
 ### Instructions
 - Write a function that takes a string and returns the biggest word in that string.
 - Make sure to remove punctuation and whitespace.
 ```
 longestWord("This string, has a gigantic! word in it...") // returns "gigantic"
 
 longestWord("one, two, three") // returns "three"
 ```
  - Note: Look up `NSCharacterSet` methods to remove whitespace and punctuation. Create the charSets as `NSMutableCharset` objects so you can combine the two CharSets. Call the `componentsSeperatedByCharacterInSet` method on the parameter string to get an array of strings after separating them by the charSets. Loop through the array to check against your return string length.
 
 ### Black Diamond 💎💎💎
 - Do this in an Objective-C project.
 */

import Foundation

extension Dictionary {
    public init(keys: [Key], values: [Value]) {
        precondition(keys.count == values.count)

        self.init()

        for (index, key) in keys.enumerated() {
            self[key] = values[index]
        }
    }
}

extension String {
    var lettersOnly: String {
        return self.components(separatedBy: CharacterSet.letters.inverted).joined()
    }
}

func longestWord(in string: String) -> String {
    
    // Break the string into words
    let words = string.components(separatedBy: .whitespacesAndNewlines)
    print(words)
    
    // Sanitize the words of punctuation
    let cleanWords = words.map { $0.lettersOnly }
    
    // Map those words into letter counts
    let letterCounts = cleanWords.compactMap{ $0.count } //{ $0.starts(with: "#")
    
    // insert those things into Dictionary to have key-value pairs
    let wordDictionary: [String: Int] = Dictionary(keys: cleanWords, values: letterCounts)
    print(wordDictionary)
    
    let longestWord = wordDictionary.max { a, b in a.value < b.value }
    
    // Return the word with the largest count
    return longestWord?.key ?? "sorry, couldn't find longest word. blame the programmer."
    
}

print(longestWord(in: "one, two, three")) // "three"

print(longestWord(in: "This string, has a gigantic! word in it...")) // "gigantic"

print(longestWord(in: "Don't trip and fall")) // could be any of the 4 letter words

print(longestWord(in: "Hello there! Come here my little friend. Don't be afraid. Don't worry, he'll be all right. What happened? Rest easy, son, you've had a busy day. You're fortunate you're still in one piece. Ben? Ben Kenobi! Boy, am I glad to see you! The Jundland wastes are not to be traveled lightly.")) // fortunate