60 minGenerally takes around 60 min to solve.

Weight tracking app

hard

Build a weight-tracker UI: the daily-log screen of a fitness app. Firebase persistence is optional for the live round; use in-memory state if the interviewer skips the backend.

Home: chronologically-sorted list of {weightKg, dateTime} entries rendered lazily via ListView.builder. Each row: weight in big text, date below, and a difference indicator (up/down arrow + delta vs the previous entry).
The AppBar + action opens a showModalBottomSheet with a decimal number input, date/time picker, and Save/Cancel buttons.
Tapping a row opens the same sheet pre-filled (edit mode) with a Delete button.
Render a card at the top of Home: current weight + total change since the first entry.

Reference UI

Acceptance criteria

Weight input accepts digits and one decimal point only.
The add/edit flow returns the new entry to the home screen.
A date picker is integrated.
The delta indicator (vs the previous entry) updates immediately when entries change.
Add, edit, and delete each reflect on the home list immediately.

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lib/main.dart

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