From c55423d6f3245e8016da1f583fcd2310f48bd658 Mon Sep 17 00:00:00 2001
From: Andrew Ekstedt <andrew.ekstedt@gmail.com>
Date: Tue, 12 Dec 2023 09:40:29 +0000
Subject: [PATCH] day 12 cleanup

---
 day12/sol2.tcl | 60 ++++++++++++++++++++++----------------------------
 1 file changed, 26 insertions(+), 34 deletions(-)

diff --git a/day12/sol2.tcl b/day12/sol2.tcl
index 7662a6c..ccdb658 100755
--- a/day12/sol2.tcl
+++ b/day12/sol2.tcl
@@ -2,27 +2,25 @@
 source ../prelude.tcl
 set input stdin
 
-array set ::m {}
-
-proc memo {row nums i left} {
+proc count-memo {row nums i left} {
+    global memo
+    if {$i == 0} {
+        array unset memo
+    }
     set key "$i,$left,[llength $nums]"
-    if {[info exists ::m($key)]} {
+    if {[info exists memo($key)]} {
         #puts "$key exists"
-        #puts [array get ::m]
-        return $::m($key)
+        return $memo($key)
     }
     set n [count $row $nums $i $left]
-    set ::m($key) $n
+    set memo($key) $n
     return $n
 }
 
 proc count {row nums i left} {
-#puts [list count $row $nums $i $left]
+    #puts [list count $row $nums $i $left]
     if {$i >= [string length $row]} {
-        if {[llength $nums] > 0} {
-            return 0
-        }
-        return [expr {$left > 1 ? 0 : 1}]
+        return [expr {($left > 1 || [llength $nums] > 0) ? 0 : 1}]
     }
     if {[llength $nums] <= 0 && $left <= 0} {
         return [expr {[string first "#" $row $i] >= 0 ? 0 : 1}]
@@ -31,70 +29,64 @@ proc count {row nums i left} {
     incr i
     if {$c eq "."} {
         if {$left > 1} {
+            # contradiction: expecting a "#"
             return 0
         } elseif {$left == 1} {
+            # left counts the number of "#" left in the current group,
+            # plus the "." at the end. if left==1 then we've seen all
+            # the "#" and now we need to see a "."
             set left 0
         } else {
             # nothing
         }
-        return [memo $row $nums $i $left]
+        return [count-memo $row $nums $i $left]
     }
     if {$c eq "#"} {
         if {$left > 1} {
             incr left -1
         } elseif {$left == 1} {
+            # contradiction: expecting a "."
             return 0
         } else {
             set nums [lassign $nums left] ;# shift nums
         }
-        return [memo $row $nums $i $left]
+        return [count-memo $row $nums $i $left]
     }
     if {$c eq "?"} {
         if {$left > 1} {
             # must be "#"
             incr left -1
             #set row [string replace $row $i-1 $i-1 "#"]
-            return [memo $row $nums $i $left]
+            return [count-memo $row $nums $i $left]
         } elseif {$left == 1} {
             # must be "."
             set left 0
             #set row [string replace $row $i-1 $i-1 "."]
-            return [memo $row $nums $i $left]
+            return [count-memo $row $nums $i $left]
         } else {
             # bifurcate
+            # "."
             #set row [string replace $row $i-1 $i-1 "."]
-            set a [memo $row $nums $i $left] ;# "."
+            set a [count-memo $row $nums $i $left]
             set nums [lassign $nums left]
+            # "#"
             #set row [string replace $row $i-1 $i-1 "#"]
-            set b [memo $row $nums $i $left] ;# "#"
+            set b [count-memo $row $nums $i $left]
             return [expr {$a + $b}]
         }
     }
     error "invalid character '$c' at position $i"
 }
 
-proc match {row nums} {
-    #puts -nonewline "  $row -> "
-    set row [string map {. " "} $row]
-    #puts "  $row"
-    foreach group $row n $nums {
-        if {[string length $group] != $n} {
-            return 0
-        }
-    }
-    return 1
-}
-
+set part1 0
 set part2 0
 while {[gets $input line] >= 0} {
-    set n 0
     lassign $line row nums
     set row "$row?$row?$row?$row?$row"
-    set row [string trim $row "."]
+    #set row [string trim $row "."]
     set nums [split $nums ","]
     set nums [concat $nums $nums $nums $nums $nums]
-    array unset ::m
-    set n [memo $row $nums 0 0]
+    set n [count-memo $row $nums 0 0]
     puts "$n | $row $nums"
     incr part2 $n
 }