AOC2019day8part1

8.sh

#!/bin/bash

set -eu


input=$(<"$1")
layers=()
width=25
height=6
area=$((width * height))

for offset in $(seq 0 "$area" "${#input}"); do
  layers+=("${input:$offset:$area}")
done

bestlayer=0
bestlayer_nonzeros=0

for layer in "${layers[@]}"; do
  nonzeros=${layer//0/}
  if [ "${#nonzeros}" -gt "$bestlayer_nonzeros" ]; then
    bestlayer=$layer
    bestlayer_nonzeros=${#nonzeros}
  fi
done

ones=$(tr -dc 1 <<<"$bestlayer")
twos=$(tr -dc 2 <<<"$bestlayer")
echo $(( ${#ones} * ${#twos}))