Think of Subsets, but here you can reuse elements and you stop when the sum reaches target. Use a start index to avoid duplicate combinations ([,] and [,] are the same). When you pick element i, recurse with start = i (not i+) to allow reusing it. Prune: if the remaining target becomes negative, stop exploring.
##### ###### ##### ### # # ### # # ###### ## ## ## ## ## ## ## # # # # # ## ##### #### ##### # # # # # # # #### ## # ## ## ## ## # # # # # ## ## # ###### ## ### # ### # ######
$ curl repovive.com/roadmaps/maang-interview-prep/backtracking/combination-sum-hint
░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░░███████████████████████████████████████████████████████████████████████████████████