Status: IN
Solutions routinely mutate input data structures (arrays, linked lists, matrices) in-place and return the same reference, blending imperative mutation with functional return-value style.
The mutate-and-return idiom matches LeetCode's expected interface pattern
Depends on (SL): in-place-mutation-return-convention, in-place-sort-mutation-pattern, assign-cookies-mutates-inputs, fused-reverse-invert