aoc2021

commit ee74ace205e37586ff7985753f7f1bdf8fccf5b2
parent e37d98bd6da6cacb94d183c5f6480b837bc5fe7a
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Mon,  6 Dec 2021 15:32:07 +0000

update comments

Diffstat:
M
day04-1.pl
 | 
45
++++++++++++++++-----------------------------

1 file changed, 16 insertions(+), 29 deletions(-)
diff --git a/day04-1.pl b/day04-1.pl
@@ -86,58 +86,38 @@ sub print_board_state {
 sub check_for_winner {
     my ($boards, $state) = @_;
     #my $found_winner = 0;
-    # check for row wins
+# check for row wins
     foreach my $board (@$boards) {       # $board is ref to board array
         foreach my $row (@$board) {      # $row is ref to board row array
             my $total = 0;
-            foreach my $column (@$row) {
+            foreach my $column (@$row) { # $column is the actual value of
+                                         # the number in @$row
                 $total += $state->{$board}{$row}{$column};
             }
             if ($total == 5) {
                 say "found row winner";
                 #$found_winner = 1;
-                return 1;
-            }
-        }
-        foreach (0 .. 4) {
-            foreach my $row (@$boards) {
-                say @{${$row}[$_]};
+                return $board;
             }
         }
+# for each board, iterate through each column (0 .. 4)
         foreach (0 .. 4) {
             my $total = 0;
             foreach my $row (@$board) {
-                #say "$board\t$_\t$row->[$_]\t$state->{$board}{$row}{$row->[$_]}";
+# here, $_ represents the index within the array @$row.  Because the hash key
+# stores the actual value, we need to deference $row (which is an array
+# reference) and then look up the value stored in the index $_
                 $total += $state->{$board}{$row}{$row->[$_]};
             }
             if ($total == 5) {
                 say "found column winner";
-                return 1;
+                return $board;
             }
         }
     }
     return 0; # no winner found
 }
 
-sub check_for_horiz_winner {
-    my ($boards, $state) = @_;
-    foreach my $board (@$boards) {       # $board is ref to board array
-        foreach (0 .. 4) {
-            foreach my $row (@$board) {
-                say "$board\t$_\t$row->[$_]\t$state->{$board}{$row}{$row->[$_]}";
-            }
-        }
-        #foreach my $row (@$board) {      # $row is ref to board row array
-#            foreach my $column (@$row) {
-#                say "$board\t$row\t$column";
-#            }
-#            foreach (0 .. 4) {
-#                say "$board\t$row\t$row->[$_]";
-#            }
-        #}
-    }
-}
-
 # Advent of Code 2021 Day 04 Part 1
 # initialize game variables
 my $filehandle  = get_filehandle();
@@ -145,6 +125,11 @@ my @numbers     = get_numbers($filehandle);
 my @boards      = initialize_boards($filehandle);
 my %state       = initialize_state(\@boards);
 my $turn = 0;
+
+# $winner_found plays double duty.  When equal to 0, it means that
+# we haven't yet found a winning board.  When we do, the subroutine
+# check_for_winner returns a reference to the array of the winning
+# board which we can then submit to calculate_score.
 my $winner_found = 0;
 
 until ($winner_found) {
@@ -157,6 +142,8 @@ until ($winner_found) {
         last;
     }
 }
+
+say "\$winner_found = $winner_found";
 #check_for_horiz_winner(\@boards, \%state);
 print_board_state(\@boards, \%state);