Method findElement

java/Chapter 11/Question11_6/QuestionB.java:19–51

(int[][] matrix, Coordinate origin, Coordinate dest, int x)

	}
	
	public static Coordinate findElement(int[][] matrix, Coordinate origin, Coordinate dest, int x) {
		if (!origin.inbounds(matrix) || !dest.inbounds(matrix)) {
			return null;
		}
		if (matrix[origin.row][origin.column] == x) {
			return origin;
		} else if (!origin.isBefore(dest)) {
			return null;
		}
		
		/* Set start to start of diagonal and end to the end of the diagonal. Since
		 * the grid may not be square, the end of the diagonal may not equal dest.
		 */
		Coordinate start = (Coordinate) origin.clone();
		int diagDist = Math.min(dest.row - origin.row, dest.column - origin.column);
		Coordinate end = new Coordinate(start.row + diagDist, start.column + diagDist);
		Coordinate p = new Coordinate(0, 0);
		
		/* Do binary search on the diagonal, looking for the first element greater than x */
		while (start.isBefore(end)) {
			p.setToAverage(start, end);
			if (x > matrix[p.row][p.column]) {
				start.row = p.row + 1;
				start.column = p.column + 1;
			} else {
				end.row = p.row - 1;
				end.column = p.column - 1;
			}
		}
		
		/* Split the grid into quadrants. Search the bottom left and the top right. */ 
		return partitionAndSearch(matrix, origin, dest, start, x);
	}
	
	public static Coordinate findElement(int[][] matrix, int x) {
		Coordinate origin = new Coordinate(0, 0);