reorder array in place, negatives first, preserve relative order within each group. thats LC stable partition basically. used 2 pass: copy out, then write back. O(n) extra space. they asked for O(1) space - thats harder, gap method. didnt get it cleanly. ~30 min

Salesforce LMTS - reorder pos/neg

reorder array in place, negatives first, preserve relative order within each group.