// Assertions - problem 1
// Assertion is a statement of *what you know*

// A pre-condition is an assertion guaranteed to be
//     true before the code executes
//     i.e. the code can rely on it

// A post-condition is an assertion guaranteed to be
//     true after the code executes
//     i.e. whatever uses your code can rely on it

    // pre : y >= 0
	// post: returns x^y
	public static int pow(int x, int y) {
		int prod = 1;
		// Point A				y>=0
		while (y > 0) {
			// Point B			y>0
			if (y % 2 == 0) {
				// Point C		y>0, y is even
				x *= x;
				y /= 2;
				// Point D		y>0, y??
			} else {
				// Point E		y>0, y is odd
				prod *= x;
				y--;
				// Point F		y>=0, y is even
			}
			// Point G			y>=0, y??
		}
		// Point H				y==0, y is even
		return prod;
	}
   Assume the method is called only if the precondition is true.  Fill in the
   table below with the words ALWAYS, NEVER or SOMETIMES.

                    y == 0              y % 2 == 0
            +---------------------+---------------------+
    Point A |                     |                     |
            +---------------------+---------------------+
    Point B |                     |                     |
            +---------------------+---------------------+
    Point C |                     |                     |
            +---------------------+---------------------+
    Point D |                     |                     |
            +---------------------+---------------------+
    Point E |                     |                     |
            +---------------------+---------------------+
    Point F |                     |                     |
            +---------------------+---------------------+
    Point G |                     |                     |
            +---------------------+---------------------+
    Point H |                     |                     |
            +---------------------+---------------------+