Trace [2, 3, 6, 7] with target 7.
Start: current = [], remaining = 7, index = 0. Try 2: current = [2], remaining = 5. Try 2 again: current = [2, 2], remaining = 3. Try 2 again: current = [2, 2, 2], remaining = 1. Try 2: remaining = -1 < 0. Backtrack. Try 3: remaining = -2 < 0. Backtrack. Backtrack to [2, 2]. Try 3: current = [2, 2, 3], remaining = 0. Found! Add to results. Backtrack to [2]. Try 3: current = [2, 3], remaining = 2. Try 3: remaining = -1. Backtrack. ...continue. Try 7: current = [7], remaining = 0. Found!
Time depends on output size. Space: recursion depth.