message: Update parallel-courses.cpp
diff: @@ -23,7 +23,7 @@ public:
  int level, u;
  tie(level, u) = q.front(); q.pop();
  --count;
  - result = max(result, level);
  + result = level;
  for (const auto& v : g[u]) {
  --in_degree[v];
  if (!in_degree[v]) {
  