A suffix array stores suffix start positions in sorted order.
highlighted = computed this step
List every suffix
Append the sentinel to the worked string, then list every suffix. The sentinel sorts before every letter, so its suffix comes first after sorting.
sentinel $ sorts first
The suffix array stores sorted start positions
The suffix array is the sorted list of suffix start positions. Sorting once lets us binary-search a pattern later, because equal prefixes sit together in the table.