Linux: Calculating total value of numbers by command

I use the following code to identify the top 3 CPU-hogging processes and return results in JSON format:

# Thanks, simon3270
cat ps.txt | sort | awk '{if (s == $1){n=n+$2}else {if (s != ""){print s " " n};s=$1;n=$2}}END{print s " " n}' | sort -rn -k +2 | awk 'BEGIN{print "{\n \"hogs\": {"}NR <= 3{printf "   \"%s\" %.1f,\n",$1,$2/10}END{print " }\n}\n"}'

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(See the attached file, ps.txt)

I want the CPU value of processes to be combined and added togeather by command.  For example:

{
 "hogs": {
   "httpd" 9,
   "ps" 0.7,
   "init" 0.1
 }
}

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Also, there should not be a comma after the last item.
ps.txt