Google Code-in

examples/tutorial/first.cc is a basic C++ program provided for ns-3 beginners. A line by line explanation of first.cc is provided in the ns-3 tutorial. Understand the working of first.cc from the tutorial, and then proceed with the following steps:

1. Copy first.cc from examples/tutorial and paste it in scratch directory.
2. Modify first.cc in scratch directory to use CSMA links instead of PointToPoint links. Use examples/tutorial/second.cc as a reference. Set the bandwidth to 100Mbps and delay to 1ms.
3. Ensure that the modified code compiles successfully.
4. Submit the patch and a screenshot of program execution for evaluation.