KV Store Serialize & Deserialize

Implement a key-value store that can serialize multiple string key-value pairs into a single string and deserialize it back. Both keys and values can contain any characters including delimiters, newlines, and special characters.

Example 1:

Input: {“a,”: “4,,5”, “b”: “”}

题目大意：

实现一个serialize和deserialize键值存储的方法。

解题思路：

用key和value的长度及自定义分隔符[][]来作为serialized的一部分，从而避开delimiter的限制.
上面的例子serialize后变成[2]a,[4]4,,5[1]b[0]

解题步骤：

N/A

注意事项：

1. 不用+=连接res，用list和join提交效率
2. 用index方法找自定义分隔符而不是逐字符处理
3. 重复代码来处理token可以放入子函数，用nonlocal不用作为输入参数且可以修改此变量

Python代码：

def serialize(kv):
    tokens = []
    for k, v in kv.items():
        tokens.append(f"[{len(k)}]{k}[{len(v)}]{v}")
    return "".join(tokens)

def deserialize(serialized):
    i = 0
    dict = {}
    while i < len(serialized):

        def get_token(s):
            nonlocal i
            token_len_st = serialized.find("[", i) + 1
            token_len_end = serialized.find("]", i)
            token_len = int(serialized[token_len_st:token_len_end])
            token_st = token_len_end + 1
            i = token_st + token_len
            return serialized[token_st:token_st + token_len]

        k = get_token(serialized)
        v = get_token(serialized)
        dict[k] = v
    return dict

算法分析：

时间复杂度为O(n)，空间复杂度O(n)

Python代码：

def serialize2(kv):
    res = ""
    for k, v in kv.items():
        res += f"[{len(k)}]{k}[{len(v)}]{v}"
    return res

def deserialize2(serialized):
    is_key = True
    i, kv_length = 0, -1
    k, v = "", ""
    dict = {}
    serialized += " "
    while i < len(serialized):
        if kv_length >= 0:
            if is_key:
                k = serialized[i:i + kv_length] # a,
            else:
                v = serialized[i:i + kv_length] # 4,,5
                dict[k] = v
            is_key = False if is_key else True
            i += kv_length
            kv_length = -1
        if serialized[i] == "[":
            st = i + 1 # 6
        elif serialized[i] == "]":
            end = i # 2
            kv_length = int(serialized[st:end]) # 4
        i += 1
    return dict