add: new input scanning exercises

23-input-scanning/exercises/03-unique-words-2/main.go

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+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+package main
+
+// ---------------------------------------------------------
+// EXERCISE: Unique Words 2
+//
+//  Use your solution from the previous "Unique Words"
+//  exercise.
+//
+//  Before adding the words to your map, remove the
+//  punctuation characters and numbers from them.
+//
+//
+// BE CAREFUL
+//
+//  Now the shakespeare.txt contains upper and lower
+//  case letters too.
+//
+//
+// EXPECTED OUTPUT
+//
+//  go run main.go < shakespeare.txt
+//
+//   There are 100 words, 69 of them are unique.
+//
+// ---------------------------------------------------------
+
+func main() {
+	// This is the regular expression pattern you need to use:
+	// [^A-Za-z]+
+	//
+	// Matches to any character but upper case and lower case letters
+}

23-input-scanning/exercises/03-unique-words-2/shakespeare.txt

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+Come, night. Come, Romeo. Come, thou day in night,
+For thou wilt lie upon the wings of night
+Whiter than new snow upon a raven’s back.
+Come, gentle night, come, loving, black-browed night,
+Give me my Romeo. And when I shall die,
+Take him and cut him out in little stars,
+And he will make the face of heaven so fine
+That all the world will be in love with night
+And pay no worship to the garish sun.
+Oh, I have bought the mansion of a love,
+But not possessed it, and though I am sold,
+Not yet enjoyed.

23-input-scanning/exercises/03-unique-words-2/solution/main.go

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+package main
+
+// For more tutorials: https://blog.learngoprogramming.com
+//
+// Copyright © 2018 Inanc Gumus
+// Learn Go Programming Course
+// License: https://creativecommons.org/licenses/by-nc-sa/4.0/
+//
+
+import (
+	"bufio"
+	"fmt"
+	"os"
+	"regexp"
+	"strings"
+)
+
+func main() {
+	in := bufio.NewScanner(os.Stdin)
+	in.Split(bufio.ScanWords)
+
+	rx := regexp.MustCompile(`[^A-Za-z]+`)
+
+	total, words := 0, make(map[string]int)
+	for in.Scan() {
+		total++
+
+		word := rx.ReplaceAllString(in.Text(), "")
+		word = strings.ToLower(word)
+		words[word]++
+	}
+
+	fmt.Printf("There are %d words, %d of them are unique.\n",
+		total, len(words))
+}

23-input-scanning/exercises/03-unique-words-2/solution/shakespeare.txt

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+Come, night. Come, Romeo. Come, thou day in night,
+For thou wilt lie upon the wings of night
+Whiter than new snow upon a raven’s back.
+Come, gentle night, come, loving, black-browed night,
+Give me my Romeo. And when I shall die,
+Take him and cut him out in little stars,
+And he will make the face of heaven so fine
+That all the world will be in love with night
+And pay no worship to the garish sun.
+Oh, I have bought the mansion of a love,
+But not possessed it, and though I am sold,
+Not yet enjoyed.