language: bash prompt: https://adventofcode.com/2020/day/5
learn:
#!/bin/bash
max_id=0
declare -a ids
for line in $(cat input); do
row=$(echo ${line:0:7} | tr FB 01)
col=$(echo ${line:7:11} | tr LR 01)
row=$((2#$row))
col=$((2#$col))
id=$((row * 8 + col))
ids+=($id)
if [[ $id -gt $max_id ]];then max_id=$id; fi
done
echo "(part 1) Max ID: $max_id"
ids=($(echo "${ids[@]}" | sed 's/ /\n/g' | sort -n))
first_id=${ids[0]}
prev_id=$((first_id - 1))
for id in ${ids[@]}; do
if [[ $prev_id -ne $(($id - 1)) ]]; then
echo "(part 2) First empty chair: $(($id - 1))"
break
fi
prev_id=$id
done