2020 day 24 (bash) part 1.

2020/day24/ex1.bash

@@ -0,0 +1,48 @@
+#!/bin/bash
+#
+# ex1.bash: Advent2020 game, day 24/game 1.
+
+CMD=${0##*/}
+shopt -s extglob
+set -o noglob
+
+declare -A plan
+declare -i x y
+
+while read -r line; do
+    x=0
+    y=0
+    for ((i=0; i<${#line}; ++i)); do
+        c=${line:i:1}
+        case "$c" in
+            e) ((++x))
+               ;;
+            w) ((--x))
+               ;;
+            s) ((--y, ++i))
+               c=${line:i:1}
+               ;;
+            n) ((++y, ++i))
+               c=${line:i:1}
+               ;;
+        esac
+        if [[ "$c" = e ]]; then
+            (( x++ ))
+        elif [[ "$c" = w ]]; then
+            (( x-- ))
+        else
+            printf "error c=%s\n" "$c"
+        fi
+    done
+    printf "new tile at (%d,%d): " "$x" "$y"
+    if [[ -v plan[$x,$y] ]]; then
+        printf "already set\n"
+        unset "plan[$x,$y]"
+    else
+        printf "new\n"
+        plan[$x,$y]=1
+    fi
+done
+res=${#plan[@]}
+printf "%s: res=%s\n" "$CMD" "$res"
+exit 0