SAP Concur Senior Software Development Engineer In Test interview questions

Supposedly to be 3 rounds apart from the first screening with the HR/recruitment co-ordinator. Round 1 with co-ordinator Round 2 with QA Manager Round 3 with fellow Senior S/w Dev Engg in Test First two rounds went absolutely great. The HR questions were all about how confident and well trained are you to work in a competitive environment. There was also a detailed discussion about the company and its recruitment process QA Manager's interview was all about test process. Tricky questions of how would you test web service and so on. Fellow Sr. Software Dev Engg : Never expect this round would become a blunder after a serious of great Q/A session in OO went smoothly, however, the question to develop an API to find longest path in binary tree killed it all. I stumbled to understand the question from the picture and the moment i did, i think the manager assumed i wasn't skilled as a java dev. Overall it went ok