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advent-of-code/2024/day-8/solution-1.sh
2024-12-09 00:36:51 +08:00

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#!/usr/bin/env bash
FILE=input
LEN=$( head -1 "$FILE" | sed -E 's/(.)/\1\ /g' | awk '{printf NF}' )
read -r -a MAP_ARRAY <<< "$( < "$FILE" sed -E 's/(.)/\1\ /g' | paste -s -d ' ' )"
read -r -a SHADOW_ARRAY <<< "$( < "$FILE" sed -E 's/(.)/\1\ /g' | paste -s -d ' ' )"
#printf "MAP_LEN: %s, NF: %s\n" "${#MAP_ARRAY[@]}" "$LEN" >&2
for CHAR in $( < "$FILE" grep -Eo '[^\.]' | sort -u | paste -s -d' ' )
do
# Get indices for antennae
LINE="$(
for (( i=0; i<${#MAP_ARRAY[@]}; i++ ))
do
if [[ ${MAP_ARRAY[i]} == "$CHAR" ]]
then
printf "%s " "$i"
fi
done
)"
#printf "%s\n" "$LINE" >&2
read -r -a IDX_ARRAY <<< "$LINE"
#printf "idx: %s " "${IDX_ARRAY[@]}" >&2
#printf "\n" >&2
# Get all combinations
for (( i=0; i<${#IDX_ARRAY[@]}-1; i++ ))
do
A=${IDX_ARRAY[i]}
for (( j=i+1; j<${#IDX_ARRAY[@]}; j++ ))
do
B=${IDX_ARRAY[j]}
DIFF=$(( B - A ))
VDIFF=$(( (B / LEN) - (A / LEN) ))
HEAD=$(( A - DIFF ))
TAIL=$(( B + DIFF ))
HEADVDIFF=$(( (A / LEN) - (HEAD / LEN) ))
TAILVDIFF=$(( (TAIL / LEN) - (B / LEN) ))
printf "char: %s, A: %s, B: %s, DIFF: %s, VDIFF: %s, HEAD: %s, HEADVDIFF: %s, TAIL: %s, TAILVDIFF: %s\n" "$CHAR" "$A" "$B" "$DIFF" "$VDIFF" "$HEAD" "$HEADVDIFF" "$TAIL" "$TAILVDIFF" >&2
# Check if out of bounds
if [[ $HEAD -lt ${#MAP_ARRAY[@]} ]] && \
[[ $HEAD -ge 0 ]] && \
[[ $HEADVDIFF -eq $VDIFF ]]
then
SHADOW_ARRAY[HEAD]=X # Mark on shadow map
echo $VALUE >> values
fi
if [[ $TAIL -lt ${#MAP_ARRAY[@]} ]] && \
[[ $TAIL -ge 0 ]] && \
[[ $TAILVDIFF -eq $VDIFF ]]
then
SHADOW_ARRAY[TAIL]=X # Mark on shadow map
echo $VALUE >> values
fi
done
done
unset IDX_ARRAY
done
printf "%s" "${SHADOW_ARRAY[@]}" | fold -w "$LEN" | sed -E 's/(.)/\1\ /g'
printf "\n"
printf "%s" "${SHADOW_ARRAY[@]}" | grep -o 'X' | wc -l