HackThisSite - Programming Mission 12

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Challenge

Level 12 — String manipulation

页面给出一串随机字符串。把所有数字取出来，按质数/合数分类（都是一位数，0 和 1 不计）：先求所有合数之和，再求所有质数之和，两者相乘得到一个乘积。然后取字符串里前 25 个非数字字符，把每个字符的 ASCII 值加一（例：# → $），把这 25 个字符与乘积首尾相接连成答案。限时 5 秒。

Your answer should look like this: oc{lujxdpb%jvqrt{luruudtx140224

Solution

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#!/usr/bin/env python3
"""Solve HackThisSite Programming Mission 12."""

import html
import os
import re

import requests

BASE = "https://www.hackthissite.org"
LEVEL_URL = f"{BASE}/missions/prog/12/"
USER_AGENT = (
    "Mozilla/5.0 (X11; Linux x86_64) AppleWebKit/537.36 "
    "(KHTML, like Gecko) Chrome/131.0.0.0 Safari/537.36"
)
PRIMES = {2, 3, 5, 7}
COMPOSITES = {4, 6, 8, 9}


def make_session():
    cookie = os.environ.get("HTS_COOKIE", "").strip().strip("'\"")
    if not cookie:
        raise SystemExit("HTS_COOKIE is not set")
    client = requests.Session()
    client.headers.update(
        {
            "User-Agent": USER_AGENT,
            "Cookie": cookie,
            "Referer": f"{BASE}/missions/programming/",
            "Accept-Language": "en-US,en;q=0.9",
        }
    )
    return client


def body_text(source):
    source = re.sub(r"<script.*?</script>", "", source, flags=re.S)
    source = re.sub(r"<br\s*/?>", "\n", source)
    source = re.sub(r"</(?:p|div|tr)>", "\n", source)
    source = re.sub(r"<[^>]+>", " ", source)
    source = html.unescape(source)
    return re.sub(r"\n\s*\n+", "\n", re.sub(r"[ \t]+", " ", source))


def parse(page_text):
    match = re.search(r'<input type="text" value="([^"]+)"', page_text)
    if match is None:
        raise SystemExit("random string not found in page")
    return match.group(1)


def solve(value):
    digits = [int(char) for char in value if char.isdigit()]
    composite_sum = sum(digit for digit in digits if digit in COMPOSITES)
    prime_sum = sum(digit for digit in digits if digit in PRIMES)
    product = composite_sum * prime_sum
    first25 = [char for char in value if not char.isdigit()][:25]
    shifted = "".join(chr(ord(char) + 1) for char in first25)
    return shifted + str(product), (composite_sum, prime_sum, product)


def verdict(response_text):
    text = body_text(response_text).lower()
    success = any(
        marker in text
        for marker in (
            "congratulation",
            "you have completed",
            "completed this",
            "successfully",
            "correct",
            "well done",
            "mission accomplished",
            "complete!",
        )
    )
    failure = any(
        marker in text
        for marker in (
            "wrong",
            "incorrect",
            "not correct",
            "try again",
            "failed",
            "too late",
            "time is up",
            "sorry",
        )
    )
    if success and not failure:
        return True
    if failure and not success:
        return False
    return None


def submit(client, answer):
    response = client.post(
        f"{LEVEL_URL}index.php",
        data={"solution": answer, "submitbutton": "submit"},
        headers={"Referer": LEVEL_URL},
        timeout=30,
    )
    response.raise_for_status()
    return verdict(response.text)


def main():
    client = make_session()
    page = client.get(LEVEL_URL, timeout=20)
    page.raise_for_status()
    value = parse(page.text)
    answer, info = solve(value)
    composite_sum, prime_sum, product = info
    print("input prefix:", value[:60])
    print(
        "sums: composite=%d prime=%d product=%d"
        % (composite_sum, prime_sum, product)
    )
    print("answer:", answer)
    print("verdict:", submit(client, answer))


if __name__ == "__main__":
    main()