Check Point Software Technologies interview questions

(task: spot the bugs and write your production level version for the correct code.) a short function called strcat (it takes two char* as input and it's task it to merge the two strings) that has a few bugs in C. for example if string 1 = "abc" and string 2 = "def" the return value (char * ) should contain "adcdef".

(task: idea, topic data structures) you get a list of event, an event is made up of the following (userID,timestamp) you need to return a list of all userIDs that had 3 events or more in an interval of 60 minutes. suggest a solution (using data structures) that solves this in the best time complexity.