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1 files changed, 48 insertions, 0 deletions

diff --git a/ch-2.pl b/ch-2.pl
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+++ b/ch-2.pl
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+#!/usr/bin/perl
+# Perl Weekly Challenge #074 Task 2 FNR character
+# task statement:
+# You are given a string $S.
+# Write a script to print the series of
+#  first non-repeating character 
+# (left -> right) for the given string. 
+#  Print # if none found.
+# Usage: ch-2.pl [string]
+
+use strict;
+use warnings;
+#use Test::More tests => 5;
+
+sub fnr {
+    my @uniquestack;
+    my %charcount;
+    my $ans = "";
+    my @characters = split //, $_[0];
+    for my $char (@characters) {
+        if (!exists $charcount{$char} ) {
+            push @uniquestack , $char;
+            $charcount{$char} = 1;
+            $ans .= $char;
+        } 
+        else {
+            $charcount{$char}++;
+            @uniquestack = grep { $charcount{$_} == 1 } @uniquestack;
+            $ans .= (scalar @uniquestack != 0) ? $uniquestack[-1]  : "#";
+        }
+    }
+    return $ans;
+
+}
+
+print fnr("$ARGV[0]");
+
+=pod
+is_deeply( fnr("ababc") , "abb#c", "example1 provided");
+is_deeply( fnr("xyzzyx") , "xyzyx#", "example2 provided");
+is_deeply( fnr("abcdef") , "abcdef", "trival");
+is_deeply( fnr("aaabbb") , "a##b##", "repeats");
+is_deeply( fnr(
+  "thequickbrownfoxjumpsoverthelazydog") , 
+  "thequickbrownffxjjmpssvvvvvvlazyddg",
+  "long sentence"
+);
+=cut