Status: IN
The merge problem family (merge-alternately, merge-nums, merge-two-lists) collectively demonstrates that pointer-per-input advancement achieves O(n+m) time with minimal allocation: each pointer advances monotonically, the merge is stable (equal-value ties broken by input ordering), and the output reuses existing nodes rather than allocating fresh ones.
Four properties of the merge family jointly characterize the pointer-advancement merge paradigm
Depends on (SL): merge-alternately-linear-complexity, merge-nums-two-pointer-linear-time, merge-no-allocation, merge-stable-ordering