Install angr. See http://angr.io/install.html
Download session-14.tgz
Switch to task-0 and first analyze the binary manually (IDA, gdb, etc). Then analyze the Angr solver: where the state starts, the avoided branches and the target state. Check that it works as expected.
Switch to task-1. The task performs a hash on the input and overwrites the return address with the function output. Use this to jump to the win() function.