// Program to test solutions to problem #2 on the cse143 midterm, winter 2020.
// Note that it does not test whether the method throws proper exceptions.
// Fill in your solution to maxDigits, then compile and run the program.

import java.util.*;
import java.io.*;

public class Test2 {
    public static int maxDigits(int x, int y) {
        // fill in your solution here
        // you can also rename the parameters above
    }

    private static int maxDigits(int n, int m, int result) {
        System.out.println("result = " + result);
        if (n < 10 && m < 10) {
            if (n % 10 > m % 10) {
                return result + n;
            } else {
                return result + m;
            }

        } else {
            if (n % 10 > m % 10) {
                return result + 10 * (n % 10) + 100 * maxDigits(n / 10, m / 10, result);
            } else {
                return result + 10 * (m % 10) + 100 * maxDigits(n / 10, m / 10, result);
            }
        }
    }

    // this is the sample solution
    public static int maxDigits2(int x, int y) {
        if (x < 0 || y < 0) {
            throw new IllegalArgumentException();
        }
        if (x == 0 && y == 0) {
            return 0;
        } else {
            return 10 * maxDigits2(x / 10, y / 10) + Math.max(x % 10, y % 10);
        }
    }

    private static int testCount;
    private static int failCount;

    public static void main(String[] args) {
        test(3509, 6238);
        test(70519, 89420615);
        test(5555, 372);
        test(246802468, 135797531);
        test(128, 394);
        test(2384, 12);
        test(9, 318);
        test(8, 5);
        test(42, 95);
        test(42, 7596);
        test(7, 0);
        test(4723, 9815);
        test(0, 0);
        test(444, 318);
        test(4, 8982);
        test(17, 22566);
        test(375, 59119);
        test(246, 8642);

        if (failCount == 0) {
            System.out.println("passed all " + testCount + " tests");
        } else {
            System.out.println("failed " + failCount + " of " + testCount + 
                               " tests");
        }
    }

    public static void test(int x, int y) {
        testOne(x, y);
        if (x != y) {
            testOne(y, x);
        }
    }

    public static void testOne(int x, int y) {
        testCount++;
        int result1 = maxDigits2(x, y);
        System.out.println("maxDigits(" + x + ", " + y + ") = " + result1);
        boolean fail = false;
        try {
            int result2 = maxDigits(x, y);
            if (result1 != result2) {
                fail = true;
                System.out.println("yours = " + result2);
            }
        } catch (RuntimeException e) {
            System.out.println("threw " + e);
            fail = true;
        }
        if (!fail) {
            System.out.println("passed");
        } else {
            failCount++;
            System.out.println("failed");
        }
        System.out.println();
    }
}