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1 files changed, 54 insertions, 0 deletions

diff --git a/ch-1.pl b/ch-1.pl
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+#!/usr/bin/perl
+# ref:
+# https://en.wikipedia.org/wiki/Boyer%E2%80%93Moore_majority_vote_algorithm
+# Perl Weekly Challenge #074 Task 1 Majority Element
+# task statement: 
+# Write a script to find the majority element. 
+# If none found then print -1.
+# Usage: ch-1.pl [ARRAY]
+use strict;
+use warnings;
+#use Test::More tests => 3;
+
+
+sub verify {
+    my @array = @{$_[0]};
+    my $m = $_[1];
+    my $c = 0;
+    for (@array) {
+        if ($m==$_) {
+            $c++;
+        }
+    }
+    return ($c > (scalar @array)/2.0 ? 1 : undef);
+}
+
+sub bm_majority_vote_alg {
+    my @array = @{$_[0]};
+    my $i = 0;
+    my $m;
+    for (@array) {
+        if ($i == 0) {
+            $m = $_;
+            $i++
+        }
+        elsif ($m == $_) {
+            $i++;
+        } 
+        else {
+            $i--;
+        }
+    }
+    
+
+    return ( verify(\@array, $m) ? $m : -1 );
+}
+
+
+print bm_majority_vote_alg(\@ARGV);
+
+=pod
+is_deeply(  bm_majority_vote_alg( [1, 2, 2, 3, 2, 4, 2] ) , "2", "example1 provided");
+is_deeply(  bm_majority_vote_alg( [1, 3, 1, 2, 4, 5] ) , "-1", "example2 provided");
+is_deeply(  bm_majority_vote_alg( [2, 2, 2, 3, 1, 3, 4] ) , "-1", "array: 2223134");
+=cut