Convolutional neural nets and backprop. That stuff is magical.
I also was fascinated as shit when I learnt about minimax and alpha beta search.
Game theory and neural nets have always fascinated me.
Ask HN: What are your favorite algorithms?
31–40 of 93 posts
Re: Ask HN: What are your favorite algorithms?
#32The Fastest and Shortest Algorithm for All Well-Defined Problems: https://arxiv.org/abs/cs/0206022 Abstract: An algorithm M is described that solves any well-defined problem p as quickly as the fastest algorithm computing a solution to p, save for a factor of 5 and low-order additive terms. M optimally distributes resources between the execution of provably correct p-solving programs and an enumeration of all proofs,…
I vote twice for this one!
Re: Ask HN: What are your favorite algorithms?
#33As basic as it is, and completely uninventive, I've always loved Dijkstra's algorithm. It was probably the algorithm that cemented my love of computer science, it's such an elegant solution to a problem and so simple once you understand it.
Why "uninventive?"
I believe GP meant that picking Dijkstra's is an uninventive answer to the question of a favorite algorithm, since it's very well-known.
Re: Ask HN: What are your favorite algorithms?
#34Given the head of a linked list, how do you determine if it loops? eg, an l-shaped list is easy to determine - you simply process each element in the list until you find one without a subsequent element. But what if it's a 9-shaped linked list? You'll never run out of elements, so the best you could seem to do would be to store a reference to each element and check against all references to see if you've found a duplicate.
There's a way to do it in O(1) space, though.
If you start off two runners in the list, and each "step" move one twice and the other only once, if there's a loop they will eventually run into each other and be processing the same element. Simple, elegant, and nothing I'd have ever thought of. :)
Re: Ask HN: What are your favorite algorithms?
#35Given the head of a linked list, how do you determine if it loops? eg, an l-shaped list is easy to determine - you simply process each element in the list until you find one without a subsequent element. But what if it's a 9-shaped linked list? You'll never run out of elements, so the best you could seem to do would be to store a reference to each element and check against all references to see if you've found a dupl…
Well... that's rather Ingenious.
Re: Ask HN: What are your favorite algorithms?
#36Ukkonen's algorithm for linear time suffix tree construction. Knuth called it 'the algorithm of 1973'.
Re: Ask HN: What are your favorite algorithms?
#37Given the head of a linked list, how do you determine if it loops? eg, an l-shaped list is easy to determine - you simply process each element in the list until you find one without a subsequent element. But what if it's a 9-shaped linked list? You'll never run out of elements, so the best you could seem to do would be to store a reference to each element and check against all references to see if you've found a dupl…
This can also be used to determine the period of Linear Congruential PRNGs, i.e those in form of
X(n+1) = (A * X(n) + B) mod C
Re: Ask HN: What are your favorite algorithms?
#38Given the head of a linked list, how do you determine if it loops? eg, an l-shaped list is easy to determine - you simply process each element in the list until you find one without a subsequent element. But what if it's a 9-shaped linked list? You'll never run out of elements, so the best you could seem to do would be to store a reference to each element and check against all references to see if you've found a dupl…
This algorithm is popularly known as "Floyd's tortoise and the hare algorithm".
Re: Ask HN: What are your favorite algorithms?
#39It looks like SWIM scales better than Raft. Are there well-known production systems that use it?
SWIM is in no way an alternative to Raft, and vice-versa. SWIM is a membership algorithm, Raft is a consensus algorithm. They are often used together. (a SWIM alternative is plain Gossip and a Raft alternative is Paxos)
Re: Ask HN: What are your favorite algorithms?
#401. Karatsuba algorithm for fast multiplication.
2. Heap's algorithm for generating permutations.
mostly because they clearly demo the power of human brain.