Binary search on the answer

Implement prototype(weights, days) and solve(weights, days). Return the smallest Number capacity that divides positive integer weights, in given order, into at most days nonempty contiguous groups. Empty weights return 0 for positive days. Weights cannot be reordered or split.

[1, 2, 3, 4, 5] with days 3 returns 6. Throw RangeError for days<=0 or any weight<=0. Prototype: enumerate capacities using a feasibility scan. Final: binary-search the capacity bound with O(1) auxiliary state. Preserve input on failure too.

All numeric inputs and finite arithmetic results in this lesson are safe-integer Numbers. Use null for documented absence, not undefined or a numeric sentinel. Return actual booleans where the contract requires them. Do not add validation requirements beyond the documented inputs.

Run with Node.js 20+ from this directory:

node main.mjs --stage prototype
node main.mjs --stage final

Edit exercise.mjs; keep main.mjs unchanged. Both stages begin as unfinished learner functions. The website uses the same test functions in a separate browser worker. Tests check deterministic examples, boundaries, documented validation, input preservation, and stage-specific cases. Passing tests does not prove the required time complexity.