the guy was senior .but he did not himself know about inner workings of hashmap.. he continouesly argued that worst case complexity is O(1) .. even i tried to make him understand that it uses linked list if collision happens etc.he did not even know what is collision.. even after that he told that from user point of view it is o(1) .. i dont care how it internally works.. !! being a senior guy how can someone say like that... i did not got any offer because of the argument happened.. even if i had got the offer.. i would not have join here..