Implement prototype(n, edges, source) and solve(n, edges, source). Vertices are Numbers 0..n-1; each edge is [u, v] and is undirected. Self-loops and parallel edges are allowed. Return distances in vertex order, with source 0 and null for unreachable vertices.
n = 3, edges = [[0, 1]], source = 0 returns [0, 1, null]. Throw RangeError for n<=0, invalid source or any endpoint outside 0..n-1.
Prototype: enumerate simple paths. Final: adjacency-list BFS in O(V+E) time/space. Preserve edges, including on validation failure.
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 finalEdit 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.
Complete the starter code, then run the checks.
Results and errors will appear here.