我正在做一个赋值，它要求我使用一个函数接受两个参数：字符串形式的整数，例如'1921'，和整数k，例如2。该函数返回最大可能的回文整数，通过将输入数字的最多k个数字更改为任何其他数字0-9可以找到。
例如，1921年最多有两次变化，最大可能的回文数是1991年（有一次变化2-
我相信我正在使用的代码检查数字是否是回文，但没有给我最大可能的回文。
使用的代码：
def Is_palindrome(str):
x = 0
for i in range (len(str)/2):
if (str[x]) == (word[len(str)-x-1]):
x+=1
if x == (len(str)/2):
return True
return False
def longest_palindrome(str):
lst = str.split()
palindromes = [] #List that contains the palindromes
long_len = 0 #Length of the longest palindrome
longest = "" #The actual longest palindrome
for i in lst:
if Is_palindrome(i): #If the str is a palindrome
palindromes.append(i) #Add it to the palindrome list
for i in palindromes: #Loop through the palindrome list
if len(i) > long_len: #If the palindrome is longer than the
longest one
longest = i #Set it as the longest one
longest_len = len(i) # Set the length of the longest one to
the length of this one
return longest
如果您有任何建议，请告诉我！！提前感谢。
请尝试以下代码：
import sys
def maximumPalinUsingKChanges(str, k):
palin = []
a = 0
b = len(str)
while (a < b):
palin.append(str[a])
a = a + 1
# Iinitialize l and r by leftmost and
# rightmost ends
l = 0
r = len(str) - 1
# first try to make string palindrome
while (l < r):
# Replace left and right character by
# maximum of both
if (str[l] != str[r]):
palin[l] = max(str[l], str[r])
palin[r] = max(str[l], str[r])
k = k - 1
l = l + 1
r = r - 1
# If k is negative then we can't make
# string palindrome
if (k < 0):
print("Not possible")
return "Not possible"
l = 0
r = len(str) - 1
while (l <= r):
# At mid character, if K>0 then change
# it to 9
if (l == r):
if (k > 0):
palin[l] = '9'
# If character at lth (same as rth) is
# less than 9
if (palin[l] < '9'):
#If none of them is changed in the
# previous loop then subtract 2 from K
# and convert both to 9
if (k >= 2 and palin[l] == str[l] and palin[r] == str[r]):
k -= 2
palin[l] = '9'
palin[r] = '9'
# If one of them is changed in the previous
# loop then subtract 1 from K (1 more is
# subtracted already) and make them 9
elif (k >= 1 and (palin[l] != str[l] or palin[r] != str[r])):
k = k - 1
palin[l] = '9'
palin[r] = '9'
l = l + 1
r = r - 1
print(''.join(palin))
return ''.join(palin)
确保k是整数
