grep和map计算两个集合交集、并集、补集

#!/usr/bin/perl
use strict;

#######################################
# 用grep 和map 获取两个列表的交集并集、补集
#######################################

my @a=("a","b","c","d","e");
my @b=("b","g","f","e");
print "列表a数据： @a ";
print "列表b数据: @b ";

my %a = map{$_ => 1} @a;
my %b = map{$_ => 1} @b;
my @c = map{$_ => 1} @a;     # => 操作符起到了hash赋值的作用

# @a @b 交集
my @inter = grep {$a{$_}} @b;    # 求交集
print "交集：@inter ";

# @a,@b 并集
my %merge = map {$_ => 1} @a,@b;       # 求并集
my @merge = keys (%merge);

print "并集：@merge ";

# @a,@b的补集@ca，@cb，即@a和@b相对于@merge的补集

my @ca = grep {!$a{$_}} @merge;
my @cb = grep {!$b{$_}} @merge;
print "@a的补集:@ca ";
print "@b的补集:@cb ";