Problem Statement

A tech conference is organised into several tracks (for example Web , Data , Mobile ). The organisers have collected a list of proposed talk records. Every record contains: the track name the start time in HH:MM the end time in HH:MM the talk title (may contain spaces) The records were typed in by hand, so they are messy: capitalisation is inconsistent, titles contain extra spaces, and some records carry unusable time values. Your job is to clean the data up and publish one collision-free schedule per track. Cleaning rules Apply these rules to every record, in this order. 1. Discard unusable records. A record is discarded (and plays no further part) if any of the following holds: the start time or the end time does not match the pattern HH:MM , i.e. exactly two digits, a colon, exactly two digits (so 9:00 , 09:0 , 0900 and 09:60 are all rejected); the hour part is greater than 23 , or the minute part is greater than 59 ; the start time is not strictly earlier than the end time. 2. Norm