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#!/usr/bin/perl
# https://perlweeklychallenge.org/blog/perl-weekly-challenge-039/
# Task #2
# Write a script to demonstrate Reverse Polish notation(RPN).
# Checkout the wiki page for more information about RPN.
# https://en.wikipedia.org/wiki/Reverse_Polish_notation
use strict;
use warnings;
die "Input required" unless @ARGV;
my @stack;
my @rpn = split / /, shift;
while (@rpn) {
my $in = shift @rpn;
if ($in =~ /^\d+$/) {
push @stack, $in;
}else{
my $num1 = pop @stack;
my $num2 = pop @stack;
push @stack, eval "$num2 $in $num1";
}
}
print "Result: ",@stack, "\n";
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