Solution

The correct answer is Option 2) 2

Given code (formatted)

int x = 128, y = 110;
do {
    if (x > y)
        x = x - y;
    else
        y = y - x;
} while (x != y);
printf("%d", x);

Key Points

• The loop implements the subtractive Euclidean algorithm for the greatest common divisor (GCD).
• At each step, the larger of x and y is reduced by the smaller. This preserves gcd(x, y).
• The loop stops when x == y; at that point both variables equal gcd(original x, original y).
• do { ... } while (x != y); ensures the body executes at least once.

Step-by-step dry run

End of loop

• Now x == y == 2, which equals gcd(128, 110).
• printf("%d", x); prints 2.

Important notes

• Because x and y stay positive and strictly decrease when unequal, the loop must terminate.
• Using repeated subtraction is equivalent to the usual Euclidean algorithm with modulo, just slower.