#271. Encode and Decode Strings | LeetCode Python Solution

Problem

LeetCode Problem

271. Encode and Decode Strings

Python Solution

class Solution:
    """
    @param: strs: a list of strings
    @return: encodes a list of strings to a single string.
    """
    def encode(self, strs):
        encoded_str = ""

        # Prefix each string in the list with string length and a pipe symbol
        # Concatenate them together into a single string
        for s in strs:
            encoded_str += str(len(s)) + ("|") + s

        return encoded_str

    """
    @param: str: A string
    @return: dcodes a single string to a list of strings
    """
    def decode(self, str):
        # Store decoded string in a list
        decoded_str_list = []
        idx = 0
        while idx < len(str):
            # Initialize ptr to idx.
            ptr = idx

            # Advance ptr to the pipe separator |
            while str[ptr] != '|':
                ptr += 1

            # Find out how many chars we need to extract
            num_of_chars = int(str[idx: ptr])

            # Extract decoded string and append it to the list
            decoded = str[ptr+1: ptr+1+num_of_chars]
            decoded_str_list.append(decoded)

            # Advance ptr to the next section to decode
            idx = ptr+1+num_of_chars
            print(idx)

        return decoded_str_list