All 3 tasks can be launched via Gradle or simply in some IDE.
Default input data provided in original task descriptions are stored in example_input.txt files in each submodule.
You can run those applications using following commands:
gradlew task1:run
gradlew task2:run
gradlew task3:run
To use a different set of data the following commands should be used:
gradlew task1:run --args="<<filepath>>"
gradlew task2:run --args="<<filepath>>"
gradlew task3:run --args="<<filepath>>"