Hamiltonian Cycles and the Traveling Salesperson Problem:
(See Exercise 3 -- which has an answer in the
book -- for another example of an argument showing that a
graph is not Hamiltonian.)
A Shortest-Path Algorithm:
In the following three exercises, also list the explored
(i.e., circled) vertices, in the order in which the algorithm
adds them. Note that doing #2 and #3 together saves some work.
There is a supplementary webpage on Complexity of Decision Problems.
Click here for answers in .pdf format.