day03/wires_2.sh

   1 #!/bin/bash
   2
   3 set -u
   4 set -e
   5
   6 # these wires should give 6
   7 #wire_1=(R8 U5 L5 D3)
   8 #wire_2=(U7 R6 D4 L4)
   9
  10 # these wires should get 159
  11 #wire_1=(R75 D30 R83 U83 L12 D49 R71 U7 L72)
  12 #wire_2=(U62 R66 U55 R34 D71 R55 D58 R83)
  13
  14 # these wires should get 135
  15 #wire_1=(R98 U47 R26 D63 R33 U87 L62 D20 R33 U53 R51)
  16 #wire_2=(U98 R91 D20 R16 D67 R40 U7 R15 U6 R7)
  17
  18 filename=${1:-input.txt}
  19
  20 # read in data from file instead
  21 exec 3<"$filename"
  22 IFS="," read -u 3 -a wire_1
  23 IFS="," read -u 3 -a wire_2
  24
  25 trace_wire() {
  26     local -n w=$1
  27     local -n b=$2
  28     local -n c=$3
  29     local -n w1cost=$4
  30     wire_number=$5
  31     cur_vert=0
  32     cur_horz=0
  33     moved=0
  34     last_replace_char="-"
  35     cost=0
  36
  37     for operation in "${w[@]}"; do
  38         direction=${operation:0:1}
  39         amount=${operation:1}
  40         case $direction in
  41             U)
  42                 operator=+
  43                 ;;
  44             D)
  45                 operator=-
  46                 ;;
  47             L)
  48                 operator=-
  49                 ;;
  50             R)
  51                 operator=+
  52                 ;;
  53         esac
  54
  55         case $direction in
  56             U|D)
  57                 for (( moved=1; moved <= $amount; moved++ )); do
  58                     cur_vert=$((cur_vert${operator}1))
  59                     cost=$((cost+1))
  60                     if [ $wire_number -eq 1 ]; then
  61                         if ! [ ${w1cost[$cur_horz,$cur_vert]+a} ]; then
  62                             w1cost[$cur_horz,$cur_vert]=$cost
  63                         fi
  64                     fi
  65                     if [ ${b[$cur_horz,$cur_vert]+a} ] && [ $wire_number -eq 2 ]; then
  66                         if [ ${b[$cur_horz,$cur_vert]} -eq 1 ]; then
  67                             cross_wires[$cur_horz,$cur_vert]=$((${w1cost[$cur_horz,$cur_vert]}+$cost))
  68                             b[$cur_horz,$cur_vert]=3
  69                         fi
  70                         continue
  71                     fi
  72                     b[$cur_horz,$cur_vert]=$wire_number
  73                 done
  74                 ;;
  75             L|R)
  76                 for (( moved=1; moved <= $amount; moved++ )); do
  77                     cur_horz=$((cur_horz${operator}1))
  78                     cost=$((cost+1))
  79                     if [ $wire_number -eq 1 ]; then
  80                         if ! [ ${w1cost[$cur_horz,$cur_vert]+a} ]; then
  81                             w1cost[$cur_horz,$cur_vert]=$cost
  82                         fi
  83                     fi
  84                     if [ ${b[$cur_horz,$cur_vert]+a} ] && [ $wire_number -eq 2 ]; then
  85                         if [ ${b[$cur_horz,$cur_vert]} -eq 1 ]; then
  86                             cross_wires[$cur_horz,$cur_vert]=$((${w1cost[$cur_horz,$cur_vert]}+$cost))
  87                             b[$cur_horz,$cur_vert]=3
  88                         fi
  89                         continue
  90                     fi
  91                     b[$cur_horz,$cur_vert]=$wire_number
  92                 done
  93                 ;;
  94         esac
  95     done
  96 }
  97
  98 declare -A board
  99 declare -A cross_wires
 100 declare -A wire_1_cost
 101 echo "Tracing first wire"
 102 trace_wire wire_1 board cross_wires wire_1_cost 1
 103 echo "Tracing second wire"
 104 trace_wire wire_2 board cross_wires wire_1_cost 2
 105
 106 echo "Wires cross at:"
 107 min_cost=-1
 108 for cross in "${!cross_wires[@]}"; do
 109     echo "  $cross ${cross_wires[$cross]}"
 110     cost=${cross_wires[$cross]}
 111     if [ $min_cost -lt 0 ] || [ $min_cost -gt $cost ]; then
 112         min_cost=$cost
 113     fi
 114 done
 115
 116 echo Min cost: $min_cost