Q84a

A sink in a directed graph is a vertex i such that there is an edge from every vertex $j \neq i$ to $i$ and there is no edge from $i$ to any other vertex. A directed graph $G$ with $n$ vertices is represented by its adjacency matrix $A$, where $A[i] [j] = 1$ if there is an edge directed from vertex $i$ to $j$ and $0$ otherwise. The following algorithm determines whether there is a sink in the graph $G$. i = 0; do { j = i + 1; while ((j < n) && E1) j++; if (j < n) E2; } while (j < n); flag = 1; for (j = 0; j < n; j++) if ((j! = i) && E3) flag = 0; if (flag) printf("Sink exists"); else printf ("Sink does not exist"); Choose the correct expressions for $E_1$ and $E_2$