In article <[EMAIL PROTECTED]>, Jason Purdy <[EMAIL PROTECTED]> writes: > Someone's gonna explain these, right? Man, I love learning this kinda stuff. > Last "hole", I learned about pop vs. shift (saving two strokes) and after > seeing this e-mail and playing around with Perl, I see that "-l" will take > care of the newline stuff for me (so I don't have to add "$_\n" to my print > statements [6 strokes there]).
Definitely have a look at the archives of some old golf. Also look at http://a108.bauhuette.haw-hamburg.de/golf/challenge.html > > Is that #*1.11%10 a number theory to get to the same number? How did someone > recognize that pattern? (my advanced calculus/comb math being a lil' rusty) In my case it was because i was thinking about how you do multiplication by hand and got thinking about this sum: ab ab ab ---- ASsb where s is the last digit of the sum of a and b, and S is the same, but with the carry from s added in. And THAT is exactly what we were supposed to calculate. The sift add pattern you get from 111. So we need the third-last digit from $num*111, which you can get by dividing by 100 and modulus 10, so you get: $num*1.11%10 Also, if a+b is small enough as not to give carry (which happens if the number is 18 or lower), you can use: $num*1.1%10 The hex() trick i found when enumerating all functions in perlfunc and thinking about which one changes behaviour at 10. Then you see that numbers < 10 get through undamaged, and 10 becomes 16 (should be 1) and they count further again. so add modulus 15 to compensate. It's only useful for the case where you have two digits from different places. you need either + or . to combine them, and that has rather low precedence, so you tend to need the parenthesis anyways, so in a sense the cost is only 6 strokes. PS: the entries in the scoreboard are not ordered by tie score. It's the entry with &&do$0 that won (better tie-score) Also a note about looping: in golf only these loops tend to happen if you need a conditional loop (unlike a fixed loop where s///eg, map and modifier for are also useful), whose lengths are sometimes a bit hard to estimate since they depend on how much you can cuddle the thing before and after: - modifier until/while length 5 upto 7 if you can't cuddle - for(1;2;3){4} length 7 but only if you can fill all slots. Therefore almost never the best loop (you can cuddle up some postfix stuff though) - &&do$0 length 6, can be 5 if you can can cause the called thing to die. Can be 5 or 4 if you can somehow write the expression so $0 becomes a result (e.g. do${some_expression} or do $0|some_expression) You can basically ignore things like redo (one entry used ..redo for.. in a way that works, but i rather think that's a perl bug), goto etc. They all end up longer. Notice that in this case the number of iterations was constrained by the input length, so s///eg, map and for based loops are also possible. Can anyone find counterexmples for other loopingstyles that can be shorter ?
