Question

我目前正在使用Codeforces problem（我不是在比赛的中间，所以它不会作弊！）我无法获得字符串比较部分由于某种原因正确。

问题的关键在于，给定一个字符串数组，我必须计算我必须删除多少列才能按字典顺序排列字符串。因此，对于第二个测试用例场景，我们已经给出了

case
care
test
code

答案应该是2，第一列和第三列被删除并导致

ae
ae
et
oe

以下是我的代码：

#some code to take the input and convert it to a list s
begin = 0
out_list = [[] for i in range(n)]
while begin < m: #m is the length of each string
    out_copy = out_list[:]
    for i in range(n): #n is the number of strings
        out_copy[i].append(s[i][begin])
    fine = True
    for i in range(1,n):
        if ''.join(out_copy[i]) < ''.join(out_copy[i-1]):
            fine = False
    if fine:
        out_list = out_copy
    begin += 1
#some code to output the result

''.join(list)应该给我一个字符串，它是列表中所有字符的串联，而<运算符应该足以让计算机返回{{1}因为False小于c，所以第一列...但是这里的某些内容一定不是正确的。发生了什么事？

Answer 1

使用此行

out_copy = out_list[:]

你制作了out_list out_list[i]。因此，out_copy[i]和out_copy[i]指的是同一个对象。

请注意，您在每次迭代时都会变异out_list[i]，因此无论fine值如何，每次迭代都会更改print out_list。您可以通过在循环中添加begin = 0 out_list = [[] for i in range(n)] while begin < m: #m is the length of each string print out_list out_copy = out_list[:] ..... .....来确认它

[[], [], [], []]
[['c'], ['c'], ['t'], ['c']]
[['c', 'a'], ['c', 'a'], ['t', 'e'], ['c', 'o']]
[['c', 'a', 's'], ['c', 'a', 'r'], ['t', 'e', 's'], ['c', 'o', 'd']]

输出

import copy
begin = 0
out_list = [[] for i in range(n)]
while begin < m: #m is the length of each string
    out_copy = copy.deepcopy(out_list)
    .....
    .....
print out_list

改为制作深层照片。

[['a', 'e'], ['a', 'e'], ['e', 't'], ['o', 'e']]

产生正确的结果

require 'openssl'

begin
  require 'origami'
rescue LoadError
  ORIGAMIDIR = "C:\RailsInstaller\Ruby1.9.3\lib\ruby\gems\1.9.1\gems\origami-1.2.4\lib"
  $: << ORIGAMIDIR
  require 'origami'
end
include Origami

# Code below is based on documentation available on
# http://www.ruby-doc.org/stdlib-1.9.3/libdoc/openssl/rdoc/OpenSSL.html
key = OpenSSL::PKey::RSA.new 2048

open 'private_key.pem', 'w' do |io| io.write key.to_pem end
open 'public_key.pem', 'w' do |io| io.write key.public_key.to_pem end

cipher = OpenSSL::Cipher::Cipher.new 'AES-128-CBC'
pass_phrase = 'Origami rocks'

key_secure = key.export cipher, pass_phrase

open 'private_key.pem', 'w' do |io|
  io.write key_secure
end

#Create the certificate

name = OpenSSL::X509::Name.parse 'CN=nobody/DC=example'

cert = OpenSSL::X509::Certificate.new
cert.version = 2
cert.serial = 0
cert.not_before = Time.now
cert.not_after = Time.now + 3600

cert.public_key = key.public_key
cert.subject = name


OUTPUTFILE = "test.pdf"

contents = ContentStream.new.setFilter(:FlateDecode)
contents.write OUTPUTFILE,
  :x => 350, :y => 750, :rendering => Text::Rendering::STROKE, :size => 30

pdf = PDF.read('Sample.pdf')


# Open certificate files

#sigannot = Annotation::Widget::Signature.new
#sigannot.Rect = Rectangle[:llx => 89.0, :lly => 386.0, :urx => 190.0, :ury => 353.0]

#page.add_annot(sigannot)

# Sign the PDF with the specified keys
pdf.sign(cert, key, 
  :method => 'adbe.pkcs7.sha1',
  #:annotation => sigannot, 
  :location => "Portugal", 
  :contact => "myemail@email.tt", 
  :reason => "Proof of Concept"
)

# Save the resulting file
pdf.save(OUTPUTFILE)

Python字符串比较无法正常工作？

1 个答案: