11.sh

#! /usr/bin/env bash
A=($(tr "L" "X" < "${1:-11.txt}"))
B=(.${A//?/.}.); for i in "${A[@]}"; do B+=(.$i.); done; B+=($B); C=("${B[@]}");
J=$(seq 1 ${#A}); I=$(seq 1 ${#A[@]}); CHANGE=($I); round=0
while [ ${#I} != 0 ]; do
    CHANGE=(); l=
    for i in $I; do
        for j in $J; do
            x=${B[i]:j:1}
            if [[ "$x" == [LX] ]]; then
                s="${B[i-1]:j-1:3}${B[i]:j-1:3}${B[i+1]:j-1:3}"
                s=${s//[L.]}; s=${s/$x}
                if [[ -z $s ]]; then x=X; elif (( ${#s} >= 4 )); then x=L; fi
            fi
            l+=$x
        done
        [ "${B[i]}" != .$l. ] && CHANGE[i-1]=1 && CHANGE[i]=1 && CHANGE[i+1]=1
        C[i]=.$l.; l=
    done
    B=("${C[@]}")
    I=${!CHANGE[*]}
    ((++round==1)) && B=("${C[@]//X/x}")
    #((round%10)) || echo "$round: ${#CHANGE[@]}"
done
ans="${B[*]}"; ans=${ans//[ L.]}
echo "11A: ${#ans}"

#A=($(< "${1:-11.txt}"))
B=(L${A//?/L}L); for i in "${A[@]}"; do B+=(L${i}L); done; B+=($B)
J=$(seq ${#A}); I=$(seq ${#A[@]}); change=1; round=0
while [ ${#change} != 0 ]; do
    change=""; C=($B); l=""
    for i in $I; do
        for j in $J; do
            x=${B[i]:$j:1}
            [[ "$x" != [LX] ]] && l+=$x && continue
            r=${B[i]:j+1}; r=${r//.}; R=${B[i]:0:j}; R=${R//.}
            s=${R: -1}${r:0:1}
            k=1; d=${B[i-k]:j-k:1}; while [ "$d" = '.' ]; do ((++k)); d=${B[i-k]:j-k:1}; done; s+=$d
            k=1; d=${B[i-k]:j:1};   while [ "$d" = '.' ]; do ((++k)); d=${B[i-k]:j:1};   done; s+=$d
            k=1; d=${B[i-k]:j+k:1}; while [ "$d" = '.' ]; do ((++k)); d=${B[i-k]:j+k:1}; done; s+=$d
            k=1; d=${B[i+k]:j-k:1}; while [ "$d" = '.' ]; do ((++k)); d=${B[i+k]:j-k:1}; done; s+=$d
            k=1; d=${B[i+k]:j:1};   while [ "$d" = '.' ]; do ((++k)); d=${B[i+k]:j:1};   done; s+=$d
            k=1; d=${B[i+k]:j+k:1}; while [ "$d" = '.' ]; do ((++k)); d=${B[i+k]:j+k:1}; done; s+=$d
            #[[ ${#s} == 8 ]] || echo "ERROR: ($s) $k = $i, $j"
            s=${s//L}
            if [[ -z $s ]]; then l+=X; elif (( ${#s} >= 5 )); then l+=L; else l+=$x; fi
        done
        [ "${B[i]}" != "L${l}L" ] && change+=1
        C+=(L${l}L); l=
    done
    C+=($B); B=("${C[@]}")
    ((++round==1)) && B=("${C[@]//X/x}")
    #((round%10)) || echo "$round: ${#change}"
done
sum="${B[*]}"; sum=${sum//[ L.]}
echo "11B: ${#sum}"