// Helene Martin, CSE 142
// Prompts the user to do addition problems until 
// the user gets three wrong.

// Extension ideas: 
// expressions tutor -- randomly pick an operator
// ask the user whether they still want to play
// problems get longer as the user makes more points
import java.util.*;

public class AdditionTutor {
	public static void main(String[] args) {
		Scanner console = new Scanner(System.in);
		Random r = new Random();
		
		/* This is the pseudocode we worked from:
		while (wrong < 3)
			generate a math problem
				how many operands? (random)
				generate each operand with +
				figure out answer
			
			prompt the user
			
			did user get it right?
			yes:
				points!!
			no:
				wrong++
		*/
		int points = 0;
		int wrong = 0;
		
		while (wrong < 3) {
			boolean win = playRound(r, console);
			
			if (win) {
				points++;
			} else {
				wrong++;
			}
		}
		
		System.out.println("You got " + points + " points");
	}
	
	// Generates one addition problem, prompts the user,
	// returns whether the user got it right or not.
	public static boolean playRound(Random r, Scanner console) {
		int operands = r.nextInt(4) + 2;
		
		int operand = r.nextInt(10) + 1;
		int answer = operand;
		System.out.print(operand);
		for (int i = 1; i < operands; i++) {
			operand = r.nextInt(10) + 1;
			System.out.print(" + " + operand);
			answer += operand;
		}
		
		System.out.print(" = ");
		int user = console.nextInt();
		
		if (user == answer) {
			return true;
		} else {
			System.out.println("Wrong!  The answer was " + answer);
			return false;
		}
	}
}