counting duplicates in a sorted sequence using command line tools
how about;
$ echo "100 100 100 99 99 26 25 24 24" \ | tr " " "\n" \ | sort \ | uniq -c \ | sort -k2nr \ | awk '{printf("%s\t%s\n",$2,$1)}END{print}'The result is :
100 399 226 125 124 2
uniq -c works for GNU uniq 8.23 at least, and does exactly what you want (assuming sorted input).
if order is not important
# echo "100 100 100 99 99 26 25 24 24" | awk '{for(i=1;i<=NF;i++)a[$i]++}END{for(o in a) printf "%s %s ",o,a[o]}'26 1 100 3 99 2 24 2 25 1