code-challenges/src/leetcode/medium/encode-and-decode-strings/encode_and_decode_strings.py at master · nwthomas/code-challenges · GitHub

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"""
https://leetcode.com/problems/encode-and-decode-strings/description

Description
Design an algorithm to encode a list of strings to a string. The encoded string is then sent over the network and is decoded back to the original list of strings.

Please implement encode and decode

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Example 1:
Input: ["lint","code","love","you"]
Output: ["lint","code","love","you"]
Explanation:
One possible encode method is: "lint:;code:;love:;you"

Example 2:
Input: ["we", "say", ":", "yes"]
Output: ["we", "say", ":", "yes"]
Explanation:
One possible encode method is: "we:;say:;:::;yes"
"""

from typing import List

DELIMITER = "π"


def encode(strs: List[str]) -> str:
    result = ""
    lengths = ""
    concatted_strs = ""
    for new_str in strs:
        new_length = str(len(new_str))
        lengths += new_length + ","
        concatted_strs += new_str
    result += lengths + DELIMITER + concatted_strs
    return result


def decode(s: str) -> List[str]:
    result = []
    sizes = []
    i = 0
    while s[i] != DELIMITER:
        current_size = ""
        while s[i] != ",":
            current_size += s[i]
            i += 1
        sizes.append(int(current_size))
        i += 1
    i += 1
    for size in sizes:
        result.append(s[i : i + size])
        i += size
    return result