A directed acyclic. graph (DAG) G is nice if G contains two vertices s and t such that every vertex in G can be reached from s and t can be reached from every vertex in G. Describe an efficient algorithm for determining whether a given DAG is nice, and analyze its time complexity. (Aim for Iinear time, i.e., O(m + n) time, where G (V, E), and IVI=n, IEI=m.) The algorithm must output, s and t if the given DAG G is nice.

3. A directed acyclic graph (DAG) G is nice if G contains two vertices s and t such that every vertex in G can be reached from s and t can be reached from every vertex in G. Describe an efficient algorithm for determining whether a given DAG is nice, and analyze its time complexity. (Aim for linear time, i.e., O(m+n) time, where G=(V,E), and V=n,E=m.) The algorithm must output, s and t if the given DAG G is nice