Contiguous allocation: first, best, worst and next fit

Problem

Simulate a contiguous memory allocator.

Input: the policy (first, best, worst or next), the memory size, then operations alloc NAME size and free NAME until the end of input. Initially memory is one hole [0, size).

Holes are kept sorted by address; a block is always placed at the start of the chosen hole. Ties: the lowest address.
Next fit starts searching at the first hole that ends after the end of the last allocated block, and wraps around.
On free, merge the freed block with adjacent holes.

Output: alloc A 200 -> [0, 200) or alloc F 180: FAILED (free 360, largest hole 150); free A -> holes [0, 200) [850, 1000). At the end: Final holes: … (or none), Free: X, largest hole: Y, failed requests: Z, and External fragmentation: P% where P = round(100 × (free − largest) / free) (0 if nothing is free).

Your solution

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