Consider the algorithm below whose input is a directed graph G with nodes 1..n and with a edges, and which for each i 1..n computes in A[i] the number of incoming edges to i.

for i 1 to n

A[i] 0

for i 1 to n edges G.allFrom(i)

foreach e edges j the target of e

A[j] A[j] + 1 Your task is, for each of the graph representations listed below, to express the running time of this algorithm , on the form (f(n, a)) with f as simple as possible. 1. G is represented by an adjacency matrix.

2. G is represented by adjacency lists.