# 11. MathQuiz

**Description:** Solve arithmetic problems as fast you can. Besides the java file, the code uses a file called best.txt. There is only one number in best.txt, the fewest seconds that the user has taken to solve the randomly generated set of arithmetic problems.

![best.txt](https://2966033381-files.gitbook.io/~/files/v0/b/gitbook-x-prod.appspot.com/o/spaces%2F-MkhKfSW-QtfQzynEsDN%2Fuploads%2Fgit-blob-de0f07dc702db05f3d9db4a26a0441553b7158a9%2FMathQuiz.jpg?alt=media)

best.txt has only one number in it, the best time (seconds) that the quiz has been completed in so far.

## Code

```java
package asu.mathquiz;
import java.io.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.util.Scanner;
public class MathQuiz {
    public static void main(String[] args) throws FileNotFoundException {
        int n = 5; //number of problems to solve
        int m = 3; //number of digits in the numbers
        int a = (int) Math.pow(10, m - 1);
        int b = (int) Math.pow(10, m) - 1;
        int n_wrong = 0;
        int best = getBest();
        Scanner input = new Scanner(System.in);
        String enter = input.nextLine();
        long start = System.currentTimeMillis();
        for (int i = 0; i < n; i++) {
            int x = getRandomInt(a, b);
            int y = getRandomInt(a, b);
            int correct = x + y;
            printProblem(x, y);
            int you = input.nextInt();
            while (correct != you) {
                n_wrong++;
                System.out.println("incorrent, try again:");
                printProblem(x, y);
                you = input.nextInt();
            }
        }
        finish(start, best, n_wrong);
    }
    
    public static void finish(long start, int best, int n_wrong) throws FileNotFoundException {
        long t = System.currentTimeMillis() - start;
        long yourTime = t / 1000;
        System.out.println("Seconds = " + yourTime);
        System.out.println("Wrong = " + n_wrong);
        if (yourTime < best) {
            System.out.println("New Best Time: " + yourTime);
            File bestFile = new File("best.txt");
            PrintWriter output = new PrintWriter(bestFile);
            output.print(yourTime);
            output.close();
        }
    }
    
    public static int getBest() throws FileNotFoundException {
        File file = new File("best.txt");
        Scanner getBest = new Scanner(file);
        int best = getBest.nextInt();
        System.out.println("Best = " + best + " seconds");
        System.out.println("Solve the following problems as quick as you can.");
        System.out.println("Hit enter to start the problems and the time");
        return best;
    }
    
    public static void printProblem(int x, int y) {
        int length = ("" + x).length();
        System.out.println("  " + x);
        System.out.println(" +" + y);
        System.out.print(" ");
        for (int j = 0; j < length; j++) {
            System.out.print("-");
        }
        System.out.println("");
    }
    
    public static int getRandomInt(int a, int b) {
        return (int) ((b + 1 - a) * Math.random() + a);
    }
}
```

## Output

```
best = 24 seconds
Solve the following problems as quick as you can.
Hit enter to start the problems and the timer.

  849
 +924
  ---
 1773
  252
 +882
  ---
1134
  929
 +477
  ---
1397
  354
 +803
  ---
1157
Seconds = 46
wrong = 0   
```