update difficulties for questions

[leo-step]

Hi Sean,

I looked over the difficulties of the questions you have listed and found two that need updating.

Maximum Subarray: Easy -> Medium
Peak Index in a Mountain Array: Easy -> Medium

Everything else looks up to date. Should fix #174.

Here is the short python script I ran if it's helpful.

Thanks!

import requests
from urllib.parse import urlparse
from questions import questions

query = '''query questionData($titleSlug: String!) {
  question(titleSlug: $titleSlug) {
    difficulty
  }
}
'''

for question in questions:
    p = urlparse(question["url"])
    title_slug = p.path.rstrip('/').split('/')[-1]
    our_difficulty = question["difficulty"]
    variables = {"titleSlug": title_slug}

    response = requests.post("https://leetcode.com/graphql",
        json={"query": query, "variables": variables}
    )

    their_difficulty = response.json()["data"]["question"]["difficulty"]

    if their_difficulty != our_difficulty:
        print(f'{question["name"]}: {our_difficulty} -> {their_difficulty}')

[seanprashad]

A very big thank you for submitting this PR @leo-step - I really appreciate it! Leetcode does update a question's difficulty every so often, but I didn't realize they have a GraphQL endpoint. If you'd be open to it, I'd love for you to submit a separate PR to get credit for your Python script - maybe we could add some lightweight docs on how to use it as well!

Update: I've opened #179 for this!

[leo-step]

Awesome, I'll see what I can do about it.

Thanks for putting this site together by the way. I've been using it for just over two months now, and it's been really helpful. Thought I could work on a couple improvements while I'm at it.