A growing platform

Build the growing list from lesson 7 yourself. A DynArray keeps its values in self.slots, a Python list whose length is always self.capacity. Unused slots hold None.

Write append(x). If the slots are full (size == capacity), make a new list of Nones twice as long, copy the stored values into it one by one, and add the number of values copied to self.copies. Then write x into the next free slot.

d = DynArray()
for x in [10, 20, 30, 40, 50]:
    d.append(x)
d.size, d.capacity, d.copies   # (5, 8, 7): copies of 1, 2 and 4
d.get(4)                       # 50

Do not call append on self.slots. The point is to see what Python’s own list does for you. The tests check the three counters and read every value back.

Limits

• Up to 200,000 appends.