A good interview for a tech lead role would look like this:
"Here's a technical problem your team is facing. Design a meeting for the team to decide what to do about it."
Most interviews focus too much on "can you yourself come up with a good design?" and not enough on real leadership.
Basic models of flocking behavior are controlled by three simple rules: 1) separation: avoid crowding neighbours (short range repulsion); 2) alignment: steer towards average heading of neighbors; 3) cohesion: steer towards average position of neighbors (long range attraction). With these three simple rules, the flock moves in an extremely realistic way.