How to install or-tools (binary)

Follow the official instructions for a binary installation, C++.
⚠️ It's a ~50MB download! It might take a while.

If you're not sure about which system you have, pick the latest Ubuntu with the "LTS" label (meaning: official release).

After the installation (the make test command must have worked):

Stay inside the ortools directoy (where you ran the successful make test command)

Run this if you use Linux:

sudo rm -f lib/libortools.so /usr/lib/libortools.so.9 /usr/lib/libortools.so
ln -s "$PWD/lib/libortools.so.9" "$PWD/lib/libortools.so"
sudo ln -s "$PWD/lib/libortools.so.9" /usr/lib/libortools.so.9
sudo ln -s "$PWD/lib/libortools.so.9" /usr/lib/libortools.so

Run this if you have a Mac:

sudo ln -s $PWD/lib/libortools.9.dylib /usr/local/lib

Create a test subdirectory right here in the current directory, i.e., the or-tools directory:
```
mkdir test
```
Go inside the test directory, download and uncompress test_ortools.tar.gz:
```
curl http://fabien.viger.free.fr/oc/test_ortools.tar.gz --output test_ortools.tar.gz
tar xf test_ortools.tar.gz
```
- Only if you have a Mac, change the Makefile like this: mv Makefile.apple Makefile
Verify that it all works:
```
make ortools_test
```
If it just works, CONGRATS! The ortools installation was successful. You can now move on to the exercise.
Else, here are some common errors:
- On Mac, you get a system prompt telling you that the libortools library isn't trusted, or something similar
  → If you have the "Run" or "Proceed" option, do it. If not, go to your system setting, in "Security" you should see a checkbox that'll allow you to run this in the future.
- ./ortools_test.test: error while loading shared libraries: libortools.so.9: cannot open shared object file: No such file or directory
  → the above set of commands related to libortools.so.9 wasn't done correctly or didn't work
- ortools_test.cc:3:10: fatal error: ortools/linear_solver/linear_solver.h: No such file or directory
  → did you create the test subdirectory in the right place? See above.
- undefined reference to `operations_research::MPSolver::~MPSolver()'
  → There's probably a problem with the Makefile. Did you unpack test.tar.gz correctly? Did you modify the Makefile?

Then, when you're doing td7, td8, etc:

Create a td7 (or td8, etc) subdirectory in the or-tools directory, just like the test subdirectory you just created
You can again go inside that subdirectory, unpack the TD's test.tar.gz (from the TD page), and you should be able to run:
```
make or_tools_test
```