millennium-bridge: daily C challenge, 27 October 2026

Your mission

Return the first second at which the sway climbs above the limit.

today's brief

London, June 10 2000. The Millennium Bridge opens and about two thousand people walk on. The deck starts swinging sideways. Walkers spread their feet to stay upright, which pushes in time with the swing, which makes the swing bigger. It shut after two days and reopened nearly two years later, with 37 dampers bolted underneath.

See it in action

first_wobble({2,2,2,2}, 4, 5): 2
first_wobble({-2,-2,-2}, 3, 0): -1
first_wobble({97}, 1, 5): 0

Your checklist

pushes holds n readings, one per second. A reading is negative on a second where the deck sheds more sway than the crowd puts in.
The sway starts at 0. Each second, add that second's reading to the sway, then treat any sway below 0 as 0.
Return the first second whose sway ends up strictly above limit.
Return -1 when the sway never gets there, including when there are no readings.

Constraints

Expected file: bridge.c
Allowed functions: None. Write every helper yourself.