
Randomized and Approximate Algorithms 555
19.1 Give a fast algorithm to 2-colour a bipartite
(meaning 2-colourable) graph.
19.2 The k-center problem is to place k facilities
(for example, fi re-stations), such that the
farthest that anyone has to travel to the nearest
fi re-station is as small as possible.
Use a greedy approach to produce a 2-
approximation.
19.3 Explain how to use an unbiased coin to
choose among 3 people. How many tosses
does your algorithm take?
19.4 Suppose you have two n-bit fi les at different
locations and they are known to differ
in exactly one bit. Give an algorithm to
determine which bit they differ in such that it
uses ...