Answer from cs61c-cm (Christopher Marcellino 15775059) for Question 2
In the before version, the loop will traverse the two-dimensional array by incrementing i each inner loop. Since the array is stored in memory as i arrays of j, the j elements are contigious in an array and the i elements of a given j are 21 elements apart from each other. Visiting each j sucessively will cause more cache hits since in a multi-word block cache the word will be in the cache since we just visited the prior element, much more often than it would in the first version.