One thing I was confused by in the lecture was how we “remember” which item lead us to each new item. The items we crossed-out in the lecture all look the same, so how did we determine from where each new discover came? In my answer below, I write out the new found nodes in order in caps to the right, and underneath each node I also mark (in lower case) the nodes which were found from it.
Then when we find Z near the end, we can follow the path from Z to z [I], then from I to i [F], then from F to f [E] … etc.
A B G
b,g
-A- B G C
b,g c
-A- -B- G C H
b,g c h
-A- -B- -G- C H E D
b,g c h e,d
-A- -B- -G- -C- H E D L
b,g c h e,d l
-A- -B- -G- -C- -H- E D L F
b,g c h e,d l f
-A- -B- -G- -C- -H- -E- D L F M
b,g c h e,d l f m
-A- -B- -G- -C- -H- -E- -D- L F M
b,g c h e,d l f m
-A- -B- -G- -C- -H- -E- -D- -L- F M I K
b,g c h e,d l f m i,k
-A- -B- -G- -C- -H- -E- -D- -L- -F- M I K
b,g c h e,d l f m i,k
-A- -B- -G- -C- -H- -E- -D- -L- -F- -M- I K Z
b,g c h e,d l f m i,k z
==> Z I F E C B A
=> ABCEFIZ