2021 templates

2021/templates/ex1.bash

@@ -0,0 +1,21 @@
+#!/bin/bash
+#
+# ex1.bash: Advent2020 game, day 3/game 1.
+
+CMD=${0##*/}
+
+XMOVE=3											  # 3 right
+
+declare -i xpos=0 ypos=0 count=0 linelen=0 modpos=0
+
+read -r line									  # ignore 1st line
+
+while read -r line; do
+	(( ypos++ ))
+	(( xpos += XMOVE ))							  # move right
+	(( linelen = ${#line} ))
+	(( modpos = (xpos % linelen) ))
+	[[ ${line:modpos:1} = \# ]] && ((count++))
+done
+printf "%s : lines:%d pos=%d found:%d\n" "$CMD" $ypos $xpos $count
+exit 0