rust / LEVEL 3
THEORY / RETRIEVAL
Collecting into a new Vec allocates a second buffer and replacing the old value discards reusable capacity. Operations such as retain, slice sorting and deduplication can mutate the existing buffer while only reducing or permuting its initialized elements.
Pointer and capacity checks are useful regression evidence for this bounded function because it never grows the vector. They are not a general performance claim: real optimization still starts from profiles, representative workloads and allocator-aware measurements.
CHECKPOINT
02 / PROFILING
Rewrite compact_readings in place. On valid inclusive bounds, retain only accepted readings, sort ascending and remove duplicates without replacing or shrinking the Vec allocation. Invalid bounds return false without mutation.
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