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by kccqzy 2656 days ago
In contrast, I find that the ability to formulate a problem using DP coorelates with whether a person is able to think in a mathematical way. In many dynamic programming problems you need to first define a function P(i,j) or some such, and then define it recursively; when proving the correctness, you use induction. The ability to grasp this recursion and induction is correlated with the level of abstract mathematical thinking a candidate is capable of.

That said, if a candidate goes to LeetCode or some other site to practice all the DP problems, then it's possible that the candidate can only solve DP problems without gaining other abilities.
1 comments
elteto 2656 days ago
Your two paragraphs are contradictory.

If someone can learn to solve just DP problems by practicing in leetcode then DP is a useless metric or proxy of someone’s ability to reason mathematically.

You should have said “the ability to solve DP problems is a good metric of the ability of a candidate to solve DP problems“. I would have agreed with you in that case :)

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smallnamespace 2656 days ago
> If someone can learn to solve just DP problems by practicing in leetcode then DP is a useless metric or proxy of someone’s ability to reason mathematically.

Metrics that can be gamed can still have a lot of signal in them because the cost of gaming the metric is higher than the benefit of gaming things.

There's a branch of game theory/economics called signalling theory that's applicable here: https://en.wikipedia.org/wiki/Signalling_theory

Also, if being able to learn completely arbitrary things is correlated with intelligence and correlated with job performance, then people who are willing to jump through that arbitrary hoop are telling you that 1) they think they're more capable (faster learners) than average 2) they're willing to put in the effort to prove it to you. Maybe you're not a getting a pure signal of mathematical ability, but some combination of drive + ability + learning fast, and you care about all three.

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pmiller2 2655 days ago
If the ability to learn completely arbitrary things is what they want to test, why not have them write an essay on the spot in Sanskrit?
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smallnamespace 2655 days ago
Dynamic programming is far from completely arbitrary. But even if it were completely arbitrary, it would still serve a useful signaling function as long as people agreed on which hoops they're supposed to jump through.

A peacock's plumage serve little useful purpose except to show how fit he is; but that purpose is essential to the survival of the species.

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jonfw 2655 days ago
It's not arbitrary, and it's not on the spot.

Dynamic programming asks them to either study or have abstract math skills. Both are good signs of competence.

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jogjayr 2656 days ago
> If someone can learn to solve just DP problems by practicing in leetcode then DP is a useless metric or proxy of someone’s ability to reason mathematically.

I'm not a fan of DP but I don't follow this logic. Does practicing maths problems for an exam make the exam a useless metric of mathematical reasoning?

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meheleventyone 2655 days ago
Depends on the exam but if the questions rarely vary much from the practice material then mathematical reasoning is definitely taking a back seat.
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