Assume that the vertices in the graph G are represented by 1....N integers, and the array LAST[] stores the shortest path information from the source vertex S to other vertices in the graph G in the following ways: LAST [W] = 0, if W = S or S to W is not connected; LAST[W] = V, if S to W is connected, is the last edge in the shortest path from S to W. Determine which is the source vertex S according to the information in the array LAST[], and find the shortest path from S to other vertices. W 1 2 3 4 5 6 7 LAST[W] 2 0 4 2 0 1 3