message: Update campus-bikes.cpp
diff: @@ -21,8 +21,8 @@ public:
  distances[i].pop_back();
  }
  while (lookup.size() < workers.size()) {
  - auto worker = min_heap.top()[1];
  - auto bike = min_heap.top()[2];
  + const auto worker = min_heap.top()[1];
  + const auto bike = min_heap.top()[2];
  min_heap.pop();
  if (!lookup.count(bike)) {
  result[worker] = bike;
  