--- /dev/null
+#!/usr/bin/perl -w
+use strict;
+
+# Given input like "Miami Springs\tFL\t33166\n" derived from patron addresses,
+# this utility will print a city and state for each zip that has the maximum
+# number of occurrences. (It does not attempt to break ties. If there is a tie,
+# the city and state that reaches the maximum first will end up winning.)
+
+my %zips;
+
+# Go through the input and tally the city-state combinations for each ZIP code
+while (<>) {
+ chomp;
+ (my $city, my $state, my $zip) = split(/\t/) or next;
+ next unless $zip =~ m/([\d]{5})/; # If it doesn't have 5 digits in a row, it's not a ZIP
+ $zip =~ s/^([\d]{5}).*$/$1/; # We only want the 5-digit ZIP
+ $state = uc($state);
+ $zips{$zip}{"$city\t$state"}++;
+}
+
+# Pick and print a winner for each ZIP code
+foreach(sort keys %zips) {
+ my $zip = $_;
+ my $max = 0;
+ my $citystate = "";
+ foreach(keys %{$zips{$zip}}) {
+ if ($zips{$zip}{$_} > $max) {
+ $max = $zips{$zip}{$_};
+ $citystate = $_;
+ }
+ }
+ print "$citystate\t$zip\n";
+}