找到字符串中最长的回文

回文是指aba 这样从左往右和从右往左读都一样的字符串。

 

思路：

# Input a string baseString

# Define a function check_palindromic_string(), this will return the string and its length if it is a palindromic string

# loop all the sub string of this baseString with check_palindromic_string to get a list of tuple. In the tuple is the palindromic string and its length

# loop the list above to find the longest spalindromic string

 

# Input a string baseString
baseString = raw_input("Please input a string : ")

# Define a function check_palindromic_string(), this will return the string and its length if it is a palindromic string
def check_palindromic_string(s):
    revers_s = s[::-1]
    if s == revers_s:
        return s,len(s)

# loop all the sub string of this baseString with check_palindromic_string to get a list of tuple. In the tuple is the palindromic string and its length
palindromic_list = []

for startIndex in xrange(len(baseString)):
    endIndex = startIndex+1
    while True:
        if check_palindromic_string( baseString[startIndex:endIndex] ):
            palindromic_list.append( check_palindromic_string( baseString[startIndex:endIndex] ) )
        endIndex += 1
        if endIndex > len(baseString):
            break

# loop the list above to find the longest spalindromic string
for t in palindromic_list:
    if t[1] > 1:
        print t