That seems more like a failure of mathematical reasoning than in programming.

kragen · on March 9, 2022

I would be amazed to meet someone who, if asked whether 3042041 was odd or even, would follow this exponential-time procedure manually. Unless the candidate was such a person, it's a failure of programming.

Apocryphon · on March 9, 2022

They just seem numerically illiterate to the point of not realizing how to determine odds or evens.

Though perhaps, if they were more competent as a programmer, they would skip decimal math altogether and use the ol' bitwise operator trick.

boring_twenties · on March 9, 2022

FWIW, gcc 10 generates identical code for `i % 2 != 0` and `i & 1 != 0` at -O1.

kragen · on March 9, 2022

Yeah, but "doesn't know about the % operator" is a lot less damning than "can only think of an exponential-time algorithm to determine if a number is even". Like, this is terrible, but it's linear time:

    char s[32];
    sprintf(s, "%d", n);
    char c = s[strlen(s) - 1];
    return c == '0' || c == '2' || c == '4' || c == '6' || c == '8';