Re^2: Happy 2006 (Golf)

[Perl Mouse]

Some golfing nitpicks:

• Instead of int(rand 2)?'':'-', you can write '-'x rand 2, saving seven characters.
• No need to quote 987654321, Perl will happely turn this integer into a string for you. This saves two characters.
• Use $` instead of pos(). Three characters.
• If you use an empty pattern in the substitution, Perl will do the right thing. Another five characters.
• Use s### instead of s[][] for one character savings.

Result:

$ perl -e'($_=987654321)=~s##$`?(qw[+ - * /],("")x4)[rand 8]:"-"x rand
+ 2#ge while 2006!=eval;print'
9+8*7+654*3-21

[BrowserUk]

I'll go along with most of that except

If you use an empty pattern in the substitution, Perl will do the right thing. Another five characters.

Without the negative lookahead, the regex will produce a very high proportion of invalid expressions because it will insert an operator at the very end of the string:

9+8*7*6*54/3-2/1-
-9-8-7*6+5/43/2+1
987+6/54321
98/7-6+5-4/321+
9*8/7/6/54-3/2-1
9/876*543/21
-9*8/76543*2-1-
-987/65-432+1*
9*8+7+65*432*1-
9876/5*43+21
9876-54321*
987/6-5-4/3-21/
9-8+7*65432+1
98765+432*1+
-9*8-7*65432-1+
9+87*6543*21
9-87*65*4-3-2*1
-987654-321+
98*76/54*32*1-
-9-876/5-432*1*
-987*654+321
9/87+6543*21
98-7654/3+21
-98*7-6-5*4321
98+7+6/5+4*3+2-1
-98+76+54*3/2+1/
9876543/21
-9-8+76-54321*

Not always, and so it can be expected to still produce occasional correct answers, but it will take much longer and somehow offends my sensibilities :)