given two strings s and t determine if they are isomorphic two strings are isomorphic if the characters in s can be replaced to get t all occurrences of a character must be replaced with another character while preserving the order of characters no two characters may map to the same character but a character may map to itself example 1 input s egg t add output true example 2 input s foo t bar output false example 3 input s paper t title output true reference https leetcode comproblemsisomorphicstringsdescription type s str type t str rtype bool type s str type t str rtype bool
def is_isomorphic(s, t):
    
    if len(s) != len(t):
        return False
    dict = {}
    set_value = set()
    for i in range(len(s)):
        if s[i] not in dict:
            if t[i] in set_value:
                return False
            dict[s[i]] = t[i]
            set_value.add(t[i])
        else:
            if dict[s[i]] != t[i]:
                return False
    return True