Add Binary Search in Perl

archive/p/perl/binary-search.pl

@@ -0,0 +1,82 @@
+#!/usr/bin/env perl
+use strict;
+use warnings;
+
+sub handle_error {
+    print "Usage: please provide a list of sorted integers (\"1, 4, 5, 11, 12\") and the integer to find (\"11\")\n";
+    exit(0);
+}
+
+sub check {
+    my ($s) = @_;
+
+    # Trim leading and trailing spaces
+    $s =~ s/^\s+//;
+    $s =~ s/\s+$//;
+
+    # Check if there are spaces in the middle
+    if ($s =~ /\s/) {
+        handle_error();
+    }
+
+    # Check if it's a valid integer
+    if ($s !~ /^-?\d+$/) {
+        handle_error();
+    }
+
+    return int($s);
+}
+
+sub convert {
+    my ($s) = @_;
+
+    if (length($s) == 0) {
+        handle_error();
+    }
+
+    my @v;
+    my @parts = split(',', $s);
+
+    foreach my $part (@parts) {
+        push @v, check($part);
+    }
+
+    return @v;
+}
+
+# Main program
+if (@ARGV < 2) {
+    handle_error();
+}
+
+my @v = convert($ARGV[0]);
+my $num = check($ARGV[1]);
+
+# Check if array is sorted
+for (my $i = 0; $i < @v - 1; $i++) {
+    if ($v[$i] > $v[$i + 1]) {
+        handle_error();
+    }
+}
+
+# Binary search
+my $start = 0;
+my $end = scalar(@v);
+my $ans = "false";
+
+while ($start < $end) {
+    my $mid = int(($start + $end) / 2);
+
+    if ($num < $v[$mid]) {
+        $end = $mid;
+    }
+    elsif ($v[$mid] < $num) {
+        $start = $mid + 1;
+    }
+    elsif ($v[$mid] == $num) {
+        $ans = "true";
+        last;
+    }
+}
+
+print "$ans\n";