Official websites use .gov
A
.gov website belongs to an official
government organization in the United States.
Secure .gov websites use HTTPS
A lock (
) or https:// means you've safely
connected to the .gov website. Share sensitive
information only on official, secure websites.
In graph (a), nodes labeled 1 and 2 have identical return-strings, but fall into different blocks. In graph (b), nodes labeled 1 and 2 have identical return-strings, and fall into the same block. Graphs (a) and (b) have identical return-indices but different block structures.
