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pcwalton's profile
Patrick Walton
Patrick Walton
Patrick Walton
@pcwalton

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Patrick Walton

@pcwalton

Research engineer at Mozilla

San Francisco, CA
pcwalton.github.io
Joined November 2009

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    Patrick Walton‏ @pcwalton 5 Jun 2019
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    In my job, if I have to, say, determine whether a linked list has a cycle in it, then I’ll Google for “determine whether a linked list has a cycle in it”. Trying to figure something out from first principles so I can make myself seem smart is a waste of my employer’s time.

    8:50 PM - 5 Jun 2019
    • 46 Retweets
    • 262 Likes
    • DeeAPT Thomas Villa Roman Lipovsky plkplk Riding Out the Timeline Acheron M Jacob Chae Milkjnho nea
    10 replies 46 retweets 262 likes
      1. Patrick Walton‏ @pcwalton 5 Jun 2019
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        Given that, it’s remarkable how coding interviews select for the exact opposite set of behaviors.

        6 replies 12 retweets 113 likes
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      1. Patrick Walton‏ @pcwalton 5 Jun 2019
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        Replying to @BRIAN_____

        What was the response?

        0 replies 0 retweets 0 likes
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      1. New conversation
      2. your least favorite construct‏ @XMPPwocky 5 Jun 2019
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        Replying to @pcwalton

        Keep cache keys, load the values if and when you need them.

        1 reply 0 retweets 3 likes
      3. Patrick Walton‏ @pcwalton 5 Jun 2019
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        Replying to @XMPPwocky

        Nope, you failed the interview. You’re supposed to use the Tortoise and the Hare algorithm. OBVIOUSLY.

        1 reply 2 retweets 23 likes
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      2. eddyb, thriving in isolation,‏ @eddyb_r 5 Jun 2019
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        Replying to @pcwalton

        at some point I learned that depth-first traversal of a graph plus a memoization map can be abused to detect cycles: instead of leaving an entry for a key x empty when entering f(x), you place an "in progress marker" - if you see that further down, cycle!

        1 reply 1 retweet 7 likes
      3. eddyb, thriving in isolation,‏ @eddyb_r 5 Jun 2019
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        Replying to @eddyb_r @pcwalton

        I would totally use this even for a linked list, because of how deviously powerful it is with just one map and no other fancy data structures also, if f has some helpful properties, you could even repeat the work within f(x) (once detecting a cycle) in a loop to get a fixpoint!

        0 replies 1 retweet 6 likes
      4. End of conversation
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      2. Oliver Michalak‏ @omichde 5 Jun 2019
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        Replying to @pcwalton @uliwitness

        Good point, I’m interested in a twist for our next interview: do you have a task at hand where the first google/SO hits are wrong/misleading?

        1 reply 1 retweet 2 likes
      3. Paul Pajo  🧢 [Jan/3➞₿  🔑∎] #Insulin4All {#HODL}‏ @pageman 6 Jun 2019
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        Replying to @omichde @pcwalton @uliwitness

        Paul Pajo  🧢 [Jan/3➞₿  🔑∎] #Insulin4All {#HODL} Retweeted Patrick Walton

        See:https://twitter.com/pcwalton/status/1136378302468243459?s=09 …

        Paul Pajo  🧢 [Jan/3➞₿  🔑∎] #Insulin4All {#HODL} added,

        Patrick Walton @pcwalton
        Note to self: “metal rust” is not an effective search query when searching for Rust bindings to the Metal library
        0 replies 0 retweets 5 likes
      4. End of conversation
      1. Cory O’Daniel‏ @coryodaniel 6 Jun 2019
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        Replying to @pcwalton

        The results for “making money from submitting web forms” isn’t that useful.

        0 replies 0 retweets 3 likes
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      2. let them eat cupcakes‏ @reiterator 7 Jun 2019
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        Replying to @a_nemecek @pcwalton

        Ah yes, the golden age of punch cards

        0 replies 0 retweets 0 likes
      3. End of conversation

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