1. relatively easy string logs manipulation. log: [id, time, in/out], max_duration: int. the job is to find id that has a out time - in time < max_duration. problem with this is that input logs are not sorted and not sanitized, meaning there can be an in but no out and vice versa. 2. input will be a list of lists of time intervals. each list represents all available time intervals (i.e. ["12:30-18:00"], ["12:15-19:00"], ["00:00-18:00"]) of one employee. the goal is to output a list of time intervals where a 15 min meeting can be arranged. a meeting can be arranged as long as 2 or more people are free. the problem hints using a 2D array to store each employee's time in a 15 min unit (96 * numOfEmp) and then scan through the array to find all available overlaps. There are two tricks here: 1. you need to find n meetings that are optimized by the number of employees that can attend, which can be done during array scanning where you can cache the number of people. then in the output you have to sort this optimized size n list by starting time. 2. using 2D array forces index usage. thus transforming an index int back to string time interval is a time wasting job (i.e. [0, 49, 2] -> '00:00-12:15')
