Duration Human Readable

Convert a duration in seconds into a compact human-readable English string.

datetime strings formatting arithmetic

Write a function `format_duration(seconds: int) -> str` that converts a non-negative number of seconds into a human-readable English duration string.

Rules:
- The output uses the largest units possible: years (365 days), days (24 hours), hours (60 minutes), minutes (60 seconds), seconds.
- Separate components with a comma and a space (', '), and use 'and' between the last two components if there are at least two.
- Each unit is singular when the count is 1, otherwise plural (e.g., '1 second', '2 seconds').
- If `seconds == 0`, return `'now'`.
- Do not include zero-value units unless the total is zero (in which case return 'now').

Examples:
- `format_duration(62)` → `'1 minute and 2 seconds'`
- `format_duration(3662)` → `'1 hour, 1 minute and 2 seconds'`
- `format_duration(31536000)` → `'1 year'`

Constraints

- `0 <= seconds <= 2_147_483_647` (fits in 32-bit signed integer)
- Complexity: O(1) time and space.

Example

>>> format_duration(1)
'1 second'
>>> format_duration(62)
'1 minute and 2 seconds'
>>> format_duration(120)
'2 minutes'
>>> format_duration(3600)
'1 hour'
>>> format_duration(3662)
'1 hour, 1 minute and 2 seconds'
>>> format_duration(0)
'now'

10 points ~15 min

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Hints

Break the total seconds into years, days, hours, minutes, and seconds using integer division and modulo.

Build a list of non-zero component strings like '2 hours' and '1 minute'.

Join the list: all but the last with ', ', then append the last with ' and ' if more than one component.

Remember that 0 seconds should return 'now'.

Pluralize: add 's' if the count is not 1.

Test Results

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