advent-of-code/2024/day-15/solution-1.sh

#!/usr/bin/env bash

MAP_FILE=input-map
DIRECTIONS_FILE=input-movements
MAP_WIDTH=$(( $( head -1 "$MAP_FILE" | wc -c ) -1 ))
#MAP_HEIGHT=$( < "$MAP_FILE" wc -l )

# Load map
read -r -a TEST_ARRAY <<< "$( < "$MAP_FILE" paste -s -d "" | sed -E 's/(.)(.)/\1 \2 /g' )"
read -r -a MAP_ARRAY <<< "$( < "$MAP_FILE" paste -s -d "" | sed -E 's/(.)(.)/\1 \2 /g' )"
printf "%s " "${MAP_ARRAY[@]}" | fold -w $(( MAP_WIDTH * 2 ))
printf "\n"
MAP_LEN=${#MAP_ARRAY[@]}

# Count boxes
BOX_COUNT=0
for (( i=0; i<MAP_LEN; i++ ))
do
  if [[ ${MAP_ARRAY[i]} == "O" ]]
  then
    (( BOX_COUNT++ ))
  fi
done
printf "Box count: %s\n" "$BOX_COUNT"

# Get robot position
for (( i=0; i<MAP_LEN; i++ ))
do
  if [[ ${MAP_ARRAY[i]} == "@" ]]
  then
    ROBOT_POSITION=$i
    break
  fi
done
printf "Robot position : %s\n" "$ROBOT_POSITION"

# Hardcode direction values
UP=$(( - MAP_WIDTH ))
DOWN=$MAP_WIDTH
LEFT=-1
RIGHT=1

# Iterate through directions
MOVES=0
while read -r DIRECTION
do

  # Interpret directions
  if [[ $DIRECTION == "^" ]]
  then
    DIRECTION_VALUE=$UP
  elif [[ $DIRECTION == "v" ]]
  then
    DIRECTION_VALUE=$DOWN
  elif [[ $DIRECTION == "<" ]]
  then
    DIRECTION_VALUE=$LEFT
  elif [[ $DIRECTION == ">" ]]
  then
    DIRECTION_VALUE=$RIGHT
  fi

  NEXT_POSITION=$(( ROBOT_POSITION + DIRECTION_VALUE ))

  if [[ ${MAP_ARRAY[$NEXT_POSITION]} == "O" ]] # Box in front
  then
    END_POSITION=$(( NEXT_POSITION + DIRECTION_VALUE ))
    while [[ ${MAP_ARRAY[$END_POSITION]} == "O" ]]
    do
      (( END_POSITION+=DIRECTION_VALUE ))
    done
    if [[ ${MAP_ARRAY[$END_POSITION]} == '#' ]]
    then
      printf "Next: %s End: %s Stacked boxes. No change.\n" "${MAP_ARRAY[$NEXT_POSITION]}" "${MAP_ARRAY[$END_POSITION]}"
      : # Boxes are stacked up against wall
    elif [[ ${MAP_ARRAY[$END_POSITION]} == "." ]]
    then
      printf "Next: %s End: %s Robot: %s Move boxes and robot\n" "${MAP_ARRAY[$NEXT_POSITION]}" "${MAP_ARRAY[$END_POSITION]}" "${MAP_ARRAY[$ROBOT_POSITION]}"
      # Move the box
      MAP_ARRAY[END_POSITION]=O
      MAP_ARRAY[NEXT_POSITION]=.
      # Move the robot
      MAP_ARRAY[ROBOT_POSITION]=.
      ROBOT_POSITION=$NEXT_POSITION
      MAP_ARRAY[ROBOT_POSITION]=@
    fi
  elif [[ ${MAP_ARRAY[$NEXT_POSITION]} == "#" ]] # Wall in front, do nothing
  then
    printf "Next: %s Skipping\n" "${MAP_ARRAY[$NEXT_POSITION]}"
    :
  elif [[ ${MAP_ARRAY[$NEXT_POSITION]} == "." ]] # Empty space, move forward
  then
    printf "Next: %s Move robot forward\n" "${MAP_ARRAY[$NEXT_POSITION]}"
    # Move the robot
    MAP_ARRAY[ROBOT_POSITION]=.
    ROBOT_POSITION=$NEXT_POSITION
    MAP_ARRAY[ROBOT_POSITION]=@
  fi
  (( MOVES++ ))

done <<< "$( < "$DIRECTIONS_FILE" paste -s -d "" | sed -E 's/(.)(.)/\1 \2 /g' | tr ' ' '\n' )"
printf "Moves: %s\n" "$MOVES"

printf "%s " "${MAP_ARRAY[@]}" | fold -w $(( MAP_WIDTH * 2 ))
printf "\n"

# Calculate GPS values for boxes
SUM=0
BOX_COUNT=0
for (( i=0; i<MAP_LEN; i++ ))
do
  if [[ ${MAP_ARRAY[i]} == "O" ]]
  then
    (( BOX_COUNT++ ))
    X=$(( i % MAP_WIDTH ))
    Y=$(( i / MAP_WIDTH * 100 ))
    GPS=$(( X + Y ))
    printf "Box %s X: %s Y: %s GPS: %s\n" "$i" "$X" "$Y" "$GPS"
    (( SUM+=GPS ))
  fi
done
printf "Sum: %s\n" "$SUM"
printf "Box count: %s\n" "$BOX_COUNT"

# Compare and test if walls have moved
for (( i=0; i<MAP_LEN; i++ ))
do
  if [[ ${TEST_ARRAY[i]} == "#" ]]
  then
    if [[ ${TEST_ARRAY[i]} != "${MAP_ARRAY[i]}" ]]
    then
    printf "Index %s Wall changed.\n" "$i"
    fi
  fi
done