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advent-of-code/2024/day-13/solution-2.sh
2024-12-13 16:38:08 +08:00

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#!/usr/bin/env bash
FILE=input
read -r -a INPUT_ARRAY <<< "$( sed -E 's/.*X[\+\=]([0-9]+), Y[\+\=]([0-9]+)/\1 \2 /g' < "$FILE" | paste -s -d " " )"
#printf "%s\n" "${INPUT_ARRAY[@]}" >&2
INPUT_LEN=${#INPUT_ARRAY[@]}
TOTAL_TOKEN=0
for (( i=0 ; i < INPUT_LEN; i+=6 ))
do
A=${INPUT_ARRAY[i]}
C=${INPUT_ARRAY[i+1]}
B=${INPUT_ARRAY[i+2]}
D=${INPUT_ARRAY[i+3]}
X=$(( 10000000000000 + ${INPUT_ARRAY[i+4]} ))
Y=$(( 10000000000000 + ${INPUT_ARRAY[i+5]} ))
# Check if moduluses are eq 0 before proceeding
I_MODULUS=$(( (B*Y - D*X) % (B*C - D*A) ))
echo "I_MODULUS: $I_MODULUS"
if [[ $I_MODULUS -eq 0 ]]
then
I=$(( ( B*Y - D*X ) / ( B*C - D*A ) )) # Button A
else
continue
fi
J_MODULUS=$(( ( X - A*I ) % B ))
echo "J_MODULUS: $J_MODULUS"
if [[ $J_MODULUS -eq 0 ]]
then
J=$(( ( X - A*I ) / B )) # Button b
else
continue
fi
# Numbers have to be positive ints
if [[ $I -lt 1 ]] || [[ $J -lt 1 ]]
then
continue
fi
{
echo "( $B*$Y - $D*$X ) / ( $B*$C - $D*$A )" >&2 # Button A
echo "( $X - $A*$I ) / $B )" >&2 # Button B
printf "Answer: I= %s, J= %s\n" "$I" "$J"
printf "Verify answer : %s to %s, %s to %s\n" "$(( A*I + B*J ))" "$X" "$(( C*I + D*J ))" "$Y"
printf "Total cost: %s\n" "$(( I*3 + J*1 ))"
} >&2
TOKEN=$(( I*3 + J*1 )) # Calculate token cost
# Verify numbers with results for positions
if ! [[ $(( A*I + B*J )) -eq $X ]] # X position
then
continue
elif ! [[ $(( C*I + D*J )) -eq $Y ]] # Y position
then
continue
else
(( TOTAL_TOKEN+=TOKEN ))
fi
done
printf "Total token: %s\n" "$TOTAL_TOKEN"