One part of the problem is the input. By reading in hours and minutes, make a function that converts hours and minutes to minutes past 9:00. To output, hours is seconds divided by 60, and seconds is second mod 60. This makes the rest of the problem easier.

Store the latest ending time of a meeting so far (initialize to 9:00) and override as necessary. Keep a variable for the amount of wasted time (in seconds). If the current meeting’s start time is after the latest ending time, then add the difference to the wasted time.

Time complexity

$\mathcal{O}(N)$

Problem

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