BFS visits nodes level by level.
Use a queue. For each level, process exactly queueSize nodes, collecting their values and enqueuing children.
The queue’s ordering ensures all nodes at depth d are processed before depth d+1.
BFS visits nodes level by level.
Use a queue. For each level, process exactly queueSize nodes, collecting their values and enqueuing children.
The queue’s ordering ensures all nodes at depth d are processed before depth d+1.