61. Which of the following problems is (are) known to be solvable in running time O n^3 ?
I. Find the shortest path from a given start vertex to a given end vertex in a directed graph on n vertices
with nonnegative integer weights.
II. Find the longest simple path from a given start vertex to a given end vertex in a directed graph on
n vertices with nonnegative integer weights.
III. Find the longest path from a given start vertex to a given end vertex in a directed acyclic graph (DAG)
on n vertices with nonnegative integer weights.
(A) I only (B) I and II only (C) I and III only (D) II and III only (E) I, II, and III
