#!/usr/bin/perl
#
# 用grep map 獲取兩個列表的交集并集、補集
#
use strict;
my @a=("a","b","c","d","e");
my @b=("b","g","f","e");
print "列表a數據： @a \n";
print "列表b數據: @b \n";
my %a = map{$_ => 1} @a;
my %b = map{$_ => 1} @b;
my @c = map{$_ => 1} @a;     # => 操作符起到了hash賦值的作用
# @a @b 交集
my @inter = grep {$a{$_}} @b;     # 求交集
print "交集：@inter \n";
# @a,@b 并集
my %merge = map {$_ => 1} @a,@b;  # 求并集
my @merge = keys (%merge);
print "并集：@merge \n";
# @a,@b的補集@ca，@cb，即@a和@b相對于@merge的補集
my @ca = grep {!$a{$_}} @merge;
my @cb = grep {!$b{$_}} @merge;
print "\@a的補集:@ca \n";
print "\@b的補集:@cb \n";