45. Dependency Resolver

function resolve(deps) {
  const res = [];
  const visited = new Set();
  function visit(node) {
    if (visited.has(node)) return;
    visited.add(node);
    (deps[node] || []).forEach(visit);
    res.push(node);
  }
  Object.keys(deps).forEach(visit);
  return res;
}