Adam D. Ruppe:
> Here's the program. It's based on one of the Python ones.
The D code is about 2.8 times slower than the Haskell version, and it has a
bug, shown here:
import std.stdio, std.bigint;
void main() {
int x = 100;
writefln("%010d", x);
BigInt bx = x;
writefln("%010d", bx);
}
Output:
0000000100
100
----------------------------
The Haskell code I've used:
-- Compile with: ghc --make -O3 -XBangPatterns -rtsopts pidigits_hs.hs
import System
pidgits n = 0 % (0 # (1,0,1)) where
i%ds
| i >= n = []
| True = (concat h ++ "\t:" ++ show j ++ "\n") ++ j%t
where k = i+10; j = min n k
(h,t) | k > n = (take (n`mod`10) ds ++ replicate (k-n) " ",[])
| True = splitAt 10 ds
j # s | n>a || r+n>=d = k # t
| True = show q : k # (n*10,(a-(q*d))*10,d)
where k = j+1; t@(n,a,d)=k&s; (q,r)=(n*3+a)`divMod`d
j&(n,a,d) = (n*j,(a+n*2)*y,d*y) where y=(j*2+1)
main = putStr.pidgits.read.head =<< getArgs
Bye,
bearophile
