Added dimdiden solution (#38)

Author: dimdiden

students/dimdiden/problems.csv

@@ -0,0 +1,13 @@
+5+5,10
+7+3,10
+1+1,2
+8+3,11
+1+2,3
+8+6,14
+3+1,4
+1+4,5
+5+1,6
+2+3,5
+3+3,6
+2+4,6
+5+2,7

students/dimdiden/quiz.go

@@ -0,0 +1,87 @@
+package main
+
+import (
+	"bufio"
+	"encoding/csv"
+	"errors"
+	"flag"
+	"fmt"
+	"io"
+	"log"
+	"os"
+	"strings"
+	"time"
+)
+
+// DEFAULTFILE is the quiz file expected to be load by default
+const DEFAULTFILE = "problems.csv"
+
+func main() {
+	// Flag block
+	file := flag.String("f", DEFAULTFILE, "specify the path to file")
+	timeout := flag.Int("t", 0, "specify the number of seconds for timeout")
+	flag.Parse()
+	// Failed if the number of seconds is negative
+	if *timeout < 0 {
+		flag.PrintDefaults()
+		os.Exit(1)
+	}
+	// Open file
+	f, err := os.Open(*file)
+	if err != nil {
+		log.Fatal(err)
+	}
+	defer f.Close()
+	// Run the main logic
+	total, correct, err := run(f, *timeout)
+	if err != nil {
+		log.Println(err)
+	}
+	fmt.Printf("Number of questions: %v\nNumber of correct answers: %v\n", total, correct)
+}
+
+// run is the main function to execute quiz app
+func run(qinput io.Reader, timeout int) (total, correct int, err error) {
+	// Reading csv file and parse it to the records var
+	r := csv.NewReader(qinput)
+	records, err := r.ReadAll()
+	if err != nil {
+		return total, correct, err
+	}
+	// Two channels. One for answers, another for timeout
+	answerChan := make(chan string)
+	timerChan := make(chan time.Time, 1)
+	// Iterate over the records
+	for _, record := range records {
+		question, expected := record[0], record[1]
+		fmt.Printf("Question: %v. Answer: ", question)
+		total++
+		// Listening for input in the separate goroutine
+		go getAnswer(answerChan)
+		// Run the timer in separate goroutine if the timeout is specified
+		if timeout > 0 {
+			go func() { timerChan <- <-time.After(time.Duration(timeout) * time.Second) }()
+		}
+		// Main select block
+		select {
+		case answer := <-answerChan:
+			if answer == expected {
+				correct++
+			}
+		case <-timerChan:
+			fmt.Println()
+			return total, correct, errors.New("Timeout reached!")
+		}
+	}
+	return total, correct, nil
+}
+
+// getAnswer func is for listening input from user
+func getAnswer(answerChan chan string) {
+	reader := bufio.NewReader(os.Stdin)
+	answer, err := reader.ReadString('\n')
+	if err != nil {
+		log.Fatal(err)
+	}
+	answerChan <- strings.Replace(answer, "\n", "", -1)
+}