aoc2021

commit e778587dd58d65a19d1efe8068bbbfe1a7749bf6
parent f45642928b8e57f47586249d48ce0315ac574da0
Author: Samir Parikh <noreply@samirparikh.com>
Date:   Sat,  4 Dec 2021 13:07:50 +0000

refactor Day 03 Part 1 solution to make it easier to understand

Diffstat:
M
day03-1.pl
 | 
22
+++++++++-------------

1 file changed, 9 insertions(+), 13 deletions(-)
diff --git a/day03-1.pl b/day03-1.pl
@@ -16,27 +16,23 @@ chomp( my @input = ( <$filehandle> ) );
 
 # Part 1
 my $len = length($input[0]) - 1; # number of bits - 1
-my %count_0      = ();
-my %count_1      = ();
 my $gamma_rate   = "";
 my $epsilon_rate = "";
 
-foreach (@input) {
-    my @diagnostic = split //;
-    for (0 .. $len) {
-        if ($diagnostic[$_]) { # bit at position $_ is 1
-            $count_1{$_}++;
+foreach my $index (0 .. $len) { # first iterate through indices...
+    my $count;
+    foreach my $line (@input) { # ...and then through the numbers/lines
+        if ( (split //, $line)[$index] ) { # if bit at position $index is 1
+            $count++; # postive or zero count means 1
         } else {
-            $count_0{$_}++;
+            $count--; # negative count means 0
         }
     }
-}
-
-for (0 .. $len) { # find which bit occurs the most at each position
-    if ($count_0{$_} > $count_1{$_}) {
+    # now see which is the most common bit at the index
+    if ($count < 0) { # most common bit at index is 0
         $gamma_rate   .= "0";
         $epsilon_rate .= "1";
-    } else {
+    } else {          # most common bit at index is 1
         $gamma_rate   .= "1";
         $epsilon_rate .= "0";
     }