2015/advent14.sh

   1 limit=${1-2503}
   2 count=0
   3 while read speed duration rest; do
   4     echo "using speed $speed, fly duration $duration, rest duration $rest"
   5     s[$count]=$speed d[$count]=$duration r[$count]=$rest points[$count]=0
   6     : $((count++))
   7 done < <(sed 's/.*fly //; s,km/s for ,,; s/seconds.*for//; s/ seconds.$//')
   8 echo "parsed details on $count racers"
   9
  10 # race speed duration rest time # reports distance in $dist for racer at time
  11 race() {
  12     local speed=$1 duration=$2 rest=$3 limit=$4
  13     dist=$((speed*duration * (limit/(duration+rest))))
  14     tail=$((limit%(duration+rest)))
  15     if [[ $tail -gt $duration ]]; then
  16         dist=$((dist+speed*duration))
  17     else
  18         dist=$((dist+speed*tail))
  19     fi
  20 }
  21 # compute time # sets max to max distance, and increments points[$n] of winners
  22 compute() {
  23     max=0
  24     local i=0
  25     while [[ $i -lt ${#s[*]} ]]; do
  26         race ${s[i]} ${d[i]} ${r[i]} $1
  27         # echo "distance $dist"
  28         [[ $dist -gt $max ]] && max=$dist
  29         : $((i++))
  30     done
  31     i=0
  32     while [[ $i -lt ${#s[*]} ]]; do
  33         race ${s[i]} ${d[i]} ${r[i]} $1
  34         [[ $dist == $max ]] && : $((points[i]++))
  35         : $((i++))
  36     done
  37 }
  38 i=0
  39 while [[ $i -lt $limit ]]; do
  40     echo "racing at second $i"
  41     compute $((++i))
  42 done
  43 echo "furthest racer at end: $max"
  44 echo ${points[*]}
  45 max=0 i=0
  46 while [[ $i -lt ${#s[*]} ]]; do
  47     [[ $max -gt ${points[i]} ]] || max=${points[i]}
  48     : $((i++))
  49 done
  50 echo "max points: $max"