diff --git a/day18/input b/day18/input
new file mode 100644
index 0000000..48a2458
--- /dev/null
+++ b/day18/input
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diff --git a/day18/sample1.in b/day18/sample1.in
new file mode 100644
index 0000000..fc7612e
--- /dev/null
+++ b/day18/sample1.in
@@ -0,0 +1,14 @@
+R 6 (#70c710)
+D 5 (#0dc571)
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+D 2 (#d2c081)
+R 2 (#59c680)
+D 2 (#411b91)
+L 5 (#8ceee2)
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diff --git a/day18/sol.tcl b/day18/sol.tcl
new file mode 100755
index 0000000..43cfd90
--- /dev/null
+++ b/day18/sol.tcl
@@ -0,0 +1,57 @@
+#!/usr/bin/env tclsh
+
+proc solve {input} {
+    set data {}
+    while {[gets $input line] >= 0} {
+        lappend data $line
+    }
+    set data [join $data]
+    set x 0
+    set y 0
+    set y0 0
+    set y1 1
+    set x0 0
+    set x1 1
+    set grid [dict create 0,0 1]
+    foreach {dir steps color} $data {
+        puts "$x $y $dir $steps $color"
+        for {set i 0} {$i < $steps} {incr i} {
+            switch $dir {
+                {U} {incr y -1}
+                {D} {incr y}
+                {L} {incr x -1}
+                {R} {incr x}
+            }
+            dict set grid $x,$y 1
+            set x0 [expr {min($x0,$x)}]
+            set y0 [expr {min($y0,$y)}]
+            set x1 [expr {max($x1,$x+1)}]
+            set y1 [expr {max($y1,$y+1)}]
+        }
+    }
+    set t 0
+    for {set y $y0} {$y < $y1} {incr y} {
+        set row ""
+        set in 0
+        for {set x $x0} {$x < $x1} {incr x} {
+            if {[dict exists $grid $x,$y]} {
+                if {[dict exists $grid $x,[expr {$y+1}]]} {
+                    set in [expr {!$in}]
+                }
+                lappend row "#"
+                incr t
+            } else {
+                if {$in} {
+                    lappend row "o"
+                    incr t
+                } else {
+                    lappend row "."
+                }
+            }
+        }
+        puts [join $row ""]
+    }
+    puts "$t"
+}
+
+solve stdin