Depth-first search, line by line

A recursive depth-first search on an adjacency matrix, one step at a time, with the call stack and the parent map.

Figure 1.5.Press Step, or use the arrow keys, to run one step of the procedure. The highlighted line is the one being run; the call stack shows the scans that are paused. Open on its own

The order in which vertices are entered is the sequence S. The parent map has the same vertices as keys, but a dictionary does not record order.