鐃緒申鐃縦わ申鐃緒申鐃�Round 2鐃緒申鐃熟わ申鐃殉ってわ申鐃暑。

LLR2006
 鐃緒申鐃淳なわ申匹鐃緒申鐃� 2.0 - ROUND 2 - ? Lightweight Language Ring
鐃緒申鐃緒申蓮鐃�Collatz予鐃循」（鰹申谷予鐃循￥申3x+1鐃緒申鐃緒申砲砲弔鐃緒申討鐃緒申鐃緒申鐃叔わ申鐃緒申
[鐃緒申略]
鐃殉わ申鐃緒申余鐃熟のわ申鐃緒申圓鐃緒申腓�鐃緒申 n 鐃祝つわ申鐃銃わ申 h(n) 鐃緒申鐃緒申茵�

鐃緒申鐃緒申泙鐃�trivial鐃緒申鐃緒申鐃緒申覆里鐃緒申鐃緒申鼻鐃�1,000,000鐃夙わ申鐃竣誌申鐃緒申鐃緒申鐃順、鐃渋わ申32bit鐃緒申鐃緒申鐃叔わ申足鐃緒申覆鐃緒申鐃�

鐃緒申鐃緒申鐃夙ワ申匹鐃緒申蝓�113383鐃叔逸申鐃獣わ申鐃緒申鐃緒申里鐃緒申鐃�

113383 鐃緒申 340150 鐃緒申 170075 鐃緒申 510226 鐃緒申 255113 鐃緒申 765340 鐃緒申 382670 鐃緒申 191335 鐃緒申 574006 鐃緒申 287003 鐃緒申 861010 鐃緒申 430505 鐃緒申 1291516 鐃緒申 645758 鐃緒申 322879 鐃緒申 968638 鐃緒申 484319 鐃緒申 1452958 鐃緒申 726479 鐃緒申 2179438 鐃緒申 1089719 鐃緒申 3269158 鐃緒申 1634579 鐃緒申 4903738 鐃緒申 2451869 鐃緒申 7355608 鐃緒申 3677804 鐃緒申 1838902 鐃緒申 919451 鐃緒申 2758354 鐃緒申 1379177 鐃緒申 4137532 鐃緒申 2068766 鐃緒申 1034383 鐃緒申 3103150 鐃緒申 1551575 鐃緒申 4654726 鐃緒申 2327363 鐃緒申 6982090 鐃緒申 3491045 鐃緒申 10473136 鐃緒申 5236568 鐃緒申 2618284 鐃緒申 1309142 鐃緒申 654571 鐃緒申 1963714 鐃緒申 981857 鐃緒申 2945572 鐃緒申 1472786 鐃緒申 736393 鐃緒申 2209180 鐃緒申 1104590 鐃緒申 552295 鐃緒申 1656886 鐃緒申 828443 鐃緒申 2485330 鐃緒申 1242665 鐃緒申 3727996 鐃緒申 1863998 鐃緒申 931999 鐃緒申 2795998 鐃緒申 1397999 鐃緒申 4193998 鐃緒申 2096999 鐃緒申 6290998 鐃緒申 3145499 鐃緒申 9436498 鐃緒申 4718249 鐃緒申 14154748 鐃緒申 7077374 鐃緒申 3538687 鐃緒申 10616062 鐃緒申 5308031 鐃緒申 15924094 鐃緒申 7962047 鐃緒申 23886142 鐃緒申 11943071 鐃緒申 35829214 鐃緒申 17914607 鐃緒申 53743822 鐃緒申 26871911 鐃緒申 80615734 鐃緒申 40307867 鐃緒申 120923602 鐃緒申 60461801 鐃緒申 181385404 鐃緒申 90692702 鐃緒申 45346351 鐃緒申 136039054 鐃緒申 68019527 鐃緒申 204058582 鐃緒申 102029291 鐃緒申 306087874 鐃緒申 153043937 鐃緒申 459131812 鐃緒申 229565906 鐃緒申 114782953 鐃緒申 344348860 鐃緒申 172174430 鐃緒申 86087215 鐃緒申 258261646 鐃緒申 129130823 鐃緒申 387392470 鐃緒申 193696235 鐃緒申 581088706 鐃緒申 290544353 鐃緒申 871633060 鐃緒申 435816530 鐃緒申 217908265 鐃緒申 653724796 鐃緒申 326862398 鐃緒申 163431199 鐃緒申 490293598 鐃緒申 245146799 鐃緒申 735440398 鐃緒申 367720199 鐃緒申 1103160598 鐃緒申 551580299 鐃緒申 1654740898 鐃緒申 827370449 鐃緒申 -1812855948

64bit鐃淑ら、1,000,000鐃殉で計誌申鐃緒申鐃緒申鐃緒申任皺随申箸鐃渋�鐃緒申襦�

鐃夙わ申鐃緒申鐃緒け鐃叔￥申鐃淑駕申鐃緒申C鐃祝わ申鐃緒申鐃緒申鐃緒申

#include <stdio.h>
#include <stdlib.h>

typedef long long I64;

#define collatz(n) ((n) == 1 ? 1 : ((n) % 2) ? (n)*3+1 : (n)/2)

I64 g(I64 n){
    I64 i = n;
    I64 result = 1;
    do {
        result++;
    }while((i = collatz(i)) != 1);
    return result;
}

I64 *h(I64 n){
    I64 i, nmax = 0, gmax = 0, gnext = 0;
    static I64 result[2];
    for (i = 1; i <= n; i++){
        gnext = g(i);
#ifdef VERBOSE
        fprintf(stderr, "g(%qd) = %qd\r", i, gnext);
#endif
        if (gnext > gmax){
            nmax = i; gmax = gnext;
        }
    }
    result[0] = nmax; result[1] = gmax;
    return result;
}

int main(int argc, char **argv){
    I64 n = 100;
    if (argc > 1){
        n = atoi(argv[1]);
    }
    I64 *hg = h(n);
    printf("h(%qd) = %qd where g(%qd) = %qd\n", n, hg[0], hg[0], hg[1]);
    return 0; /* so -Wall is happy */
}

MacBook Pro 2GHz鐃叔の実行件申未蓮鐃緒申焚鐃緒申里箸鐃緒申蝓�

% gcc -Wall -O3 iterative.c
% /usr/bin/time ./a.out 1000000
h(1000000) = 837799 where g(837799) = 525
        3.19 real         3.13 user         0.01 sys

C, C++, Perl鐃熟居申鐃緒申弔鐃緒申鐃曙た鐃緒申鐃緒申Haskell, Ruby, Python 鐃緒申鐃緒申鐃緒申鐃熟デフワ申鐃緒申箸鐃�bignum鐃淑のわ申OK鐃緒申鐃緒申鐃緒申鐃緒申呂覆鐃緒申鐃緒申覆鐃緒申鐃�Perl鐃塾常申鐃�-Duse64bitint鐃緒申鐃春わ申鐃緒申compile鐃緒申鐃曙た鐃緒申里任鐃緒申鐃緒申1,000,000鐃緒申鐃旬指わ申鐃暑。use bignum鐃叔わ申OK鐃緒申鐃緒申鐃緒申鐃緒申速鐃醇え鐃緒申鐃緒申鐃潤し鐃淑わ申鐃緒申

Dan the Integral Man

鐃宿居申:id:palmo鐃緒申鐃緒申里茲�鐃緒申鐃俊ット演算鐃叔わ申鐃緒申鐃祝￥申發�鐃暑が鐃緒申鐃緒申鐃塾常申鐃叔わ申鐃熟わ申113383鐃叔逸申鐃獣わ申鐃緒申鐃暑。鐃淑駕申鐃緒申鐃緒申鐃准ワ申鐃緒申鐃宿と件申漫鐃�

iterative.pl 
use strict;
use warnings;

sub g($) {
    use integer;
    my $num = shift;
    my $n = $num;
    my $step = 1;
    while ($n > 1) {
        $n = ($n & 1) ? (3 * $n + 1) : ($n >> 1);
        $step++;
    }
    die "g($num) got $n!" unless $n == 1;
    return $step;
}

sub h{
    my $n = shift;
    my ($nmax, $gmax, $gnext) = (0, 0, 0);
    for (1..$n){
        my $gnext = g($_);
        print STDERR "g($_) = $gnext\r";
        next unless $gnext > $gmax;
        $nmax = $_;
        $gmax = $gnext;
    }
    return ($nmax, $gmax);
}

sub printh{
    my $n = shift;
    my ($h, $g) = h($n);
    print "h($n) = $h where g($n) = $g\n";
}

my $n = shift || 100;
printh $n;
__END__
鐃渋行件申鐃�: 
% perl -V | grep 64bit
    use64bitint=undef use64bitall=undef uselongdouble=undef
% perl iterative.pl 1000000
g(113383) got -1812855948! at iterative.pl line 13.

鐃宿居申^2

鐃緒申鐃�ita鐃緒申鐃緒申鐃銃縁申鐃緒申箸鐃緒申妊魯泙辰討襦�

JGeek Log - 3n+1 鐃緒申鐃緒申
1000000 鐃緒申int 鐃塾ワ申鐃緒申鐃出￥申鐃春ワ申鐃緒申鐃緒申鐃緒申鐃緒申襦�