148 lines
3.0 KiB
Bash
148 lines
3.0 KiB
Bash
#!/usr/bin/env bash
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FILE=input
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MAP_WIDTH=$(( $( head -1 "$FILE" | wc -c ) -1 ))
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MAP_LEN=$( < "$FILE" wc -l )
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read -r -a MAP_ARRAY <<< "$( paste -s -d "" <"$FILE" | sed -E 's/(.)(.)/\1 \2 /g' )"
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printf "%s " "${MAP_ARRAY[@]}"
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printf "\n"
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MAP_SIZE=${#MAP_ARRAY[@]}
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for (( i=0; i<MAP_SIZE ; i++ ))
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do
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if [[ ${MAP_ARRAY[i]} -eq 0 ]]
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then
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printf "Trailhead found at position %s\n" "$i"
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TRAILHEADS+=( "$i" )
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elif [[ ${MAP_ARRAY[i]} -eq 9 ]]
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then
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printf "Peak found at position %s\n" "$i"
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PEAKS+=( "$i" )
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fi
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done
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printf "%s " "${TRAILHEADS[@]}"
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printf "\n"
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printf "%s " "${PEAKS[@]}"
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printf "\n"
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get_nine () {
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# Trails are explored areas
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# Paths are areas to explore
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GET_NUM=$1
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DIRECTIONS=$2
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TRAIL=$3
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COMBINATIONS=()
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# For each direction, get multiplication of prime number
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# corresponding to each direction
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# Modulus for valid directions is 0
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# 2 : Up
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# 3 : Down
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# 7 : Left
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# 13 : Right
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if [[ $(( DIRECTIONS % 2 )) -eq 0 ]]
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then
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INDEX=$(( TRAIL - MAP_WIDTH ))
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if [[ ${MAP_ARRAY[INDEX]} -eq $GET_NUM ]]
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then
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COMBINATIONS+=( "$INDEX" )
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fi
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fi
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if [[ $(( DIRECTIONS % 3 )) -eq 0 ]]
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then
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INDEX=$(( TRAIL + MAP_WIDTH ))
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if [[ ${MAP_ARRAY[INDEX]} -eq $GET_NUM ]]
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then
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COMBINATIONS+=( "$INDEX" )
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fi
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fi
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if [[ $(( DIRECTIONS % 7 )) -eq 0 ]]
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then
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INDEX=$(( TRAIL - 1 ))
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if [[ ${MAP_ARRAY[INDEX]} -eq $GET_NUM ]]
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then
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COMBINATIONS+=( "$INDEX" )
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fi
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fi
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if [[ $(( DIRECTIONS % 13 )) -eq 0 ]]
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then
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INDEX=$(( TRAIL + 1 ))
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if [[ ${MAP_ARRAY[INDEX]} -eq $GET_NUM ]]
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then
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COMBINATIONS+=( "$INDEX" )
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fi
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fi
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printf "Get: %s \n" "$GET_NUM" >&2
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printf "trail: %s \n" "$TRAIL" >&2
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printf "neighbors found : %s \n" "${COMBINATIONS[@]}" >&2
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# Check if the end has been reached
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# or no matching neighbors
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if [[ $GET_NUM -eq 9 ]] || [[ ${#COMBINATIONS[@]} -eq 0 ]]
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then
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# Exit recursion
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printf "%s" "${#COMBINATIONS[@]}"
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return
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fi
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# Recurse
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TOTAL=0
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NEXT_NUM=$(( GET_NUM+=1 ))
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for INDEX in "${COMBINATIONS[@]}"
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do
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COUNT=$(
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get_nine \
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"$NEXT_NUM" \
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"$( get_valid_neighbors "$INDEX" )" \
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"$INDEX"
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)
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(( TOTAL+=COUNT ))
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done
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printf "%s" "$TOTAL"
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}
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get_valid_neighbors () {
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IDX=$1
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NUM=1
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# Basically check for bounds
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# For each direction, get multiplication of prime number
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# corresponding to each direction
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# 2 : Up
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# 3 : Down
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# 7 : Left
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# 13 : Right
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if [[ $(( IDX / MAP_LEN )) -gt 0 ]]
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then
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(( NUM*=2 ))
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fi
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if [[ $(( IDX / MAP_LEN )) -le $MAP_LEN ]]
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then
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(( NUM*=3 ))
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fi
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if [[ $(( IDX % MAP_WIDTH )) -ne 0 ]]
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then
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(( NUM*=7 ))
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fi
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if [[ $(( IDX % MAP_WIDTH )) -ne $(( MAP_WIDTH - 1 )) ]]
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then
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(( NUM*=13 ))
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fi
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printf "%s" "$NUM"
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}
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PATH_COUNT=0
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ITER=999999
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for TRAILHEAD in "${TRAILHEADS[@]}"
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do
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COUNT=$( get_nine "1" "$( get_valid_neighbors "$TRAILHEAD" )" "$TRAILHEAD" )
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(( PATH_COUNT+=COUNT ))
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(( ITER-- ))
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if [[ $ITER -eq 0 ]] ;then break; fi
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done
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printf "%s\n" "$PATH_COUNT"
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