Python处理重复字符

def find_duplicates(string):
    char_set = set(string)
    if len(string) != len(char_set):
        return True
    else:
        return False

def find_duplicates(string):
    char_dict = {}
    for char in string:
        if char in char_dict:
            char_dict[char] += 1
        else:
            char_dict[char] = 1
    for count in char_dict.values():
        if count > 1:
            return True
    return False

def find_duplicates(string):
    char_list = list(string)
    for i in range(len(char_list)):
        if i != char_list.index(char_list[i]):
            return True
    return False

s = "ATAT is a repeated word"
s_new = s.replace("ATAT", "A")
print(s_new)  # "A is a repeated word"

import re

s = "loooove jaaaaava"
s_new = re.sub(r'(.)\1+', r'\1', s)
print(s_new)  # "love java"

s = "Python is awesome!"
count = s.count('o')
print(count)  # 2

def longest_common_substring(s1, s2):
    n1, n2 = len(s1), len(s2)
    lcs = [[0] * (n2 + 1) for _ in range(n1 + 1)]
    result = ""
    for i in range(n1):
        for j in range(n2):
            if s1[i] == s2[j]:
                lcs[i+1][j+1] = lcs[i][j] + 1
                if lcs[i+1][j+1] > len(result):
                    result = s1[i-lcs[i+1][j+1]+1: i+1]
    return result

s = "mississippi"
result = longest_common_substring(s, s[::-1])
print(result)  # "issi"