2015/advent20.sh

   1 house=${1-0}
   2 target=${2-33100000}
   3 got=0
   4 max=0
   5 while [[ $got -lt $target ]]; do
   6     (( house++ % 1000 )) || echo " $((house-1)) at $got, max $max"
   7     if [[ $house == 1 ]]; then
   8         got=11
   9         max=11
  10         continue
  11     fi
  12     got=$(((house + (house <= 50))*11))
  13     odd=$((house&1))
  14     i=$((2+$odd))
  15     while (( i <= 50 && i*i < house )); do
  16         if ! (( house % i )); then
  17             # echo "  $house $i"
  18             got=$((got + (house/i)*11))
  19             ((house/i <= 50)) && got=$((got + i*11))
  20         fi
  21         i=$((i+1+odd))
  22     done
  23     (( i <= 50 && i*i == house )) && got=$((got + i*11))
  24     # echo " house $house got $got"
  25     [[ $max -lt $got ]] && max=$got
  26 done
  27 echo "house $house got $got gifts"