(Exercise 22.1-6) Most graph algorithms that take an adjacency-matrix representation as input require time (V2), but there are some exceptions. Explain (in English or in pseudocode) how to determine whether a directed graph G contains a universal sinka vertex with in-degree |V|-1 and out-degree 0in time O(V), given an adjacency matrix for G. Then, briefly explain why your algorithm is O(V).