Lecture 21

Learning objectives

After this class, you should be able to:

1. Derive the cache complexity of the cache oblivious algorithm discussed in class.
2. Given an algorithm that is cache-inefficient, modify it to make it more efficient.

Reading assignment

1. Handout on cache oblivious algorithms.
2. Review selection (finding the kth largest number from a list on N numbers).

Exercises and review questions

• Questions on current lecture's material
  1. A typical mergesort implementation uses recursion, leading to a depth first traversal of the mergesort tree. We can alternatively implement it to perform a breadth first traversal. Which implementation will make better use of cache?
  2. Which of the following algorithms is likely to be the most cache efficient: (i) mergesort, (ii) quicksort, and (iii) heapsort?

• Questions on next lecture's material
  1. None.