Trace piles = [3, 6, 7, 11] with h = 8.
Search space: [1, 11].
left = 1, right = 11. mid = 6. Hours = 1 + 1 + 2 + 2 = 6 <= 8. Works. Search left: right = 5.
left = 1, right = 5. mid = 3. Hours = 1 + 2 + 3 + 4 = 10 > 8. Too slow. Search right: left = 4.
left = 4, right = 5. mid = 4. Hours = 1 + 2 + 2 + 3 = 8 <= 8. Works. Search left: right = 3.
left = 4 > right = 3. Done. Minimum speed = 4.
Binary search takes iterations where . Each iteration computes hours in . Total: time, space.