1. Let the multi-LCS problem be defined as follows.  The input is a set of m
length-n sequences X_i, 0 <= i < m.  The output is a longest sequence Y such
that Y is a subsequence of every X_i.  Use dynamic programming to develop an
algorithm for the multi-LCS problem that runs in polynomial time for any fixed
constant m.

2. Suppose we want to make change for n cents using coins of arbitrary
denominations d_r > d_{r-1} > ... > d_1 > d_0 = 1, for which the greedy
algorithm may not work.  Design an O(rn) time and O(r + n) space algorithm for
the problem using dynamic programming.

3. Exercise 23.3-10.  (Hint: First identify which edges are disallowed
in a singly connected graph.  Then use depth-first search to solve the
problem.)

4. Problem 25.3.

5. Prove or disprove: If an edge e of an MST crosses a cut C, then e is
a light edge for C.

