2025-08-29

Encode and Decode Strings

Encode List of strs to a single str and then decode a single string back to the list of strings

1

• Simplest solution is use the length of the string followed by a delimiter to indicate where to find the next string
• "foo", "bar", "baz" will become "3;foo3;bar3;baz"
• Start with the first char scan till you reach a ;. That is the length
• Have a counter and decrement for each char you scan when it hits 0 add that string to the list
• Repeat
• The problem with this is that when the lengths of the string becomes large but it is given that they are capped at 200

    def encode(self, strs):
        res = ""
        for str_ in strs:
            res += str(len(str_)) + ";" + str_
        return res

    def decode(self, s):
        res = []
        i = 0
        while i < len(s):
            tmp = ""
            start = i
            length_of_length = 0
            while s[i] != ";":
                tmp += s[i]
                i += 1
                length_of_length += 1
            tmp = int(tmp)
            res.append(
                s[start + length_of_length + 1 : start + length_of_length + tmp + 1]
            )
            i += tmp + 1
        return res