G'day NetWallah,

"After adding this test case: [[-5,-3,1,4,7], 1, [1,3]], kcott's code fails that test case, but mine passes."

Well spotted and thanks for reporting the bug.

I had added

next INNER if $input->[$j] > $target;
[download]

on the basis that a single comparison was less processing than the addition plus comparison in

if ($input->[$i] + $input->[$j] == $target) {
[download]

I thought that was a handy logic short-circuit; however, I hadn't taken into account negative numbers. I've removed that line and the INNER label: all tests now pass.

"Also - kcott's code assumes and takes advantage of the input being sorted - input order is NOT specified in the problem definition."

I don't know where you got that idea from. I neither made that assumption nor wrote any code taking advantage of such sorting. Note [[3,2,4], 6, [1,2]] which has unsorted input.