When should you sleep

When Should You Go to Sleep?

Challenge Difficulty: Medium | Estimated completion time: ~25 minutes

You’re setting an alarm for the next morning and know how long you want to sleep.
Your job is to figure out what time you need to go to bed to get that amount of sleep.

Each input has two parts:

1. The alarm time (when you’ll wake up).
2. The sleep duration (how long you want to sleep).

Return the time you should go to bed — in 24-hour format ("HH:MM").

Examples

bedTime(["07:50", "07:50"])
output = ["00:00"]
 
bedTime(["06:15", "10:00"], ["08:00", "10:00"], ["09:30", "10:00"])
output = ["20:15", "22:00", "23:30"]
 
 
bedTime(["05:45", "04:00"], ["07:10", "04:30"])
output = ["01:45", "02:40"]

Solution

Python

def bedTime(*time_pairs: list[str]) -> list[str]: """ Calculate what time to go to bed given alarm time and desired sleep duration. Args: *time_pairs: Variable number of [alarm_time, sleep_duration] pairs in HH:MM format. Returns: List of bedtimes in 24-hour format (HH:MM). Examples: >>> bedTime(["07:50", "07:50"]) ['00:00'] >>> bedTime(["06:15", "10:00"], ["08:00", "10:00"]) ['20:15', '22:00'] """ results = [] for time_pair in time_pairs: alarm_time = time_pair[0] sleep_duration = time_pair[1] # Parse alarm time alarm_hour, alarm_minute = map(int, alarm_time.split(":")) alarm_total_minutes = alarm_hour * 60 + alarm_minute # Parse sleep duration duration_hour, duration_minute = map(int, sleep_duration.split(":")) duration_total_minutes = duration_hour * 60 + duration_minute # Calculate bedtime bedtime_minutes = alarm_total_minutes - duration_total_minutes # Handle negative values (previous day) if bedtime_minutes < 0: bedtime_minutes += 24 * 60 # Convert back to hours and minutes bedtime_hour = bedtime_minutes // 60 bedtime_minute = bedtime_minutes % 60 results.append(f"{bedtime_hour:02d}:{bedtime_minute:02d}") return results if __name__ <span class="text-highlight"> "__main__": # Test cases assert bedTime(["07:50", "07:50"]) </span> ["00:00"] assert bedTime(["06:15", "10:00"], ["08:00", "10:00"], ["09:30", "10:00"]) <span class="text-highlight"> ["20:15", "22:00", "23:30"] assert bedTime(["05:45", "04:00"], ["07:10", "04:30"]) </span> ["01:45", "02:40"] print("All test cases passed!")

Output