#!/usr/bin/sh
#
# Counts from 1 to max and prints numbers whose digits
# don't repeat. Displays the biggest jump and the total
# count of numbers.
# Author: sharfah
max=$1
counter=1
prev=$counter
maxdiff=0
total=0
while ( [ $counter -le $max ] )
do
echo $counter | grep '\(.\).*\1' > /dev/null
if [ $? -ne 0 ]
then
echo "$counter"
total=`expr $total + 1`
diff=`expr $counter - $prev`
if [ $diff -gt $maxdiff ]
then
maxdiff=$diff
from=$prev
to=$counter
fi
prev=$counter
fi
counter=`expr $counter + 1`
done
echo "Biggest jump is $maxdiff:$from->$to"
echo "Total count of numbers is $total"
OutputRun on an Intel(R) Xeon(R) CPU 2.33GHz 8 CPU, SUSE LINUX Enterprise Server 9, it produced:
sharfah@starship:~> time ./beust.sh 10000 > beust.log 38.68s real 12.71s user 25.80s system sharfah@starship:~> tail beust.log 9867 9870 9871 9872 9873 9874 9875 9876 Biggest jump is 105:1098->1203 Total count of numbers is 5274When run on Solaris 10, it took 1m26.219s. If you think you can make this go faster, let me know how in the comments section!
I came in looking for a search engine plugin howto, and lost... an embarrassing amount of time. Thanks for the plugin post, that was very useful.
ReplyDeleteYou can get a bit of a speedup on your shellscript by not spawning so many greps. My beust2.sh:
yes "" | head -$1 | cat -n | tr -d [:blank:] | grep -v '\(.\).*\1' | \
(
total=0;
maxdiff=0;
from=0;
to=0;
while read current;
do
echo $current;
total=`expr 0$total + 1`;
diff=`expr $current - 0$last`;
if [ $diff -gt 0$maxdiff ];
then
maxdiff=$diff;
from=$current;
to=$last;
fi;
last=$current;
done;
echo "Biggest jump is $maxdiff:$from->$to";
echo "Total count of numbers is $total";
)
And times:
beust.sh 10000
user 0m37.758s
beust2.sh 10000
user 0m9.613s
I couldn't think of a way to get the largest gap - maybe there's a way using sort and uniq on tagged numbers? I think I'll hand over the baton... hey! I even got an Olympics ref in!