I think for O(1) in each category you can write "have conceived, designed, and implemented" a log(n) concept, construct, or tool. data structures: creator of s

I think for O(1) in each category you can write "have conceived, designed, and implemented" a log(n) concept, construct, or tool. data structures: creator of skip lists algorithms: creator of genetic algoritms systems programming: lead engineer on JVM HotSpot source control: "subversion sucks, here's Git" build automations: creators of Maven etc. (You can go down the whole list and figure out exactly what O(1) is and who belongs to that set.)