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python : Checking for a possible palindrome

There is a simple task, here is the literal condition:

Anna wrote a beautiful string generator. She thinks the line is beautiful if it reads equally from left to right and from right to left. For example, rrr and anna are pretty strings, but abc and adba are not.

But she made a mistake in the code and the generator does not output pretty lines, and the lines that can be made beautiful if you remove from each exactly one character. At least she thinks so.

She asks you to help determine if her assumption is correct.

Input data format

The first line contains a string s consisting of small Latin letters (4≤ | s | ≤10 ^ 3, where | s | is the string length).

Output format

Print YES if you can remove one character from the string so that it became beautiful; otherwise -NO.

Sample Input 1: abca Sample Output 1: YES

Sample Input 2: abcd Sample Output 2: NO

My solution (also commonplace): 

def f ():
    s= '' .join (input (). split ())
    n= len (s)
    v= 0
    for i in range (int (n /2)):
        if s [i]!= s [n-1-i]:
            v += 1
            if v>1:
                return ('NO')
    if v== 0:
        return ('NO')
    if v <2:
        return ('YES')
print (f ())

BUT, to my surprise, code fails the tests . The catch is that I don't know the input for all tests. And looking at the problem and the code, I can't understand the reason. Am I missing something? ..

What will your code give to abab input?

Yaant2021-02-23 07:14:00

at least, your code does not take into account upper /lower cases, specials and spaces.

Evgeniy Shubin2021-02-23 07:14:00

@EvgeniyShubin does not have to take into account the input string s consisting of small Latin letters

slippyk2021-02-23 07:14:00

check your function on the word banana;)

MaxU2021-02-23 07:14:00
python python-3.x алгоритм
  • Answer # 1 
    def check (beautiful_string):
    middle= len (beautiful_string) /2
    is_odd= False
    if (len (beautiful_string)% 2):
        is_odd= True
    pop_count= 0
    index= 0
    reverse_index= -1
    while (index <= middle):
        if (beautiful_string [index]!= beautiful_string [reverse_index]):
            if (pop_count>0):
                return 'NO'
            index += 1
            if (beautiful_string [index]== beautiful_string [reverse_index]):
                pop_count += 1
                middle -= 1
                continue
            index -= 1
            reverse_index -= 1
            if (beautiful_string [index]== beautiful_string [reverse_index]):
                pop_count += 1
                continue
            return 'NO'
        index += 1
        reverse_index -= 1
    if (pop_count== 1):
        return 'YES'
    if (pop_count== 0) and (is_odd):
        return 'YES'
    return 'NO'
  • Answer # 2

    Try it: 

    def foo (text):
    for i in range (len (text)):
        items= list (text)
        items.pop (i)
        if items== items [:: -1]:
            return 'YES'
    return 'NO'
print (foo ("abca")) # YES
print (foo ("abcd")) # NO
print (foo ("abab")) # YES
print (foo ('banana')) # YES