Answer by NikoNyrh for Tweetable hash function challenge
Here are a few similar constructs, which are quite "seedable" and makes incremental parameter optimization possible. Damn it is difficult to get lower than 6k! Assuming the score has the mean of 6829...
View ArticleAnswer by Magenta for Tweetable hash function challenge
Python 3, 89 bytes, 6534 hash collisions def H(x): v=846811 for y in x: v=(972023*v+330032^ord(y))%2**24 return v%2**24 All the large magic numbers you see here are fudge constants.
View ArticleAnswer by Shieru Asakoto for Tweetable hash function challenge
JavaScript, 121 bytes, 3268 3250 3244 6354(3185) collisions s=>{v=i=0;[...s].map(z=>{v=((((v*13)+(s.length-i)*7809064+i*380886)/2)^(z.charCodeAt(0)*266324))&16777215;i++});return v}...
View ArticleAnswer by Kevin Kenny for Tweetable hash function challenge
tcl 88 bytes, 6448 / 3233 collisions I see people have been counting either the number of colliding words, or else the number of words placed in nonempty buckets. I give both counts - the first is...
View ArticleAnswer by sergiol for Tweetable hash function challenge
tcl #91 bytes, 6508 collisions 91 bytes, 6502 collisions proc H s {lmap c [split $s ""] {incr h [expr [scan $c %c]*875**[incr i]]};expr $h&0xFFFFFF} Computer is still performing a search to...
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Answer by Anders Kaseorg for Tweetable hash function challenge
Alright fine I’ll go learn a golfing language. CJam, 140 bytes, 3314 colliding words 00000000: 7b5f 3162 225e d466 4a55 a05e 9f47 fc51 {_1b"^.fJU.^.G.Q 00000010: c45b 4965 3073 72dd e1b4 d887 a4ac bcbd...
View ArticleAnswer by Dennis for Tweetable hash function challenge
CJam, 4125 3937 3791 3677 0000000: 7b 5f 39 62 31 31 30 25 5f 22 7d 13 25 77 {_9b110%_"}.%w 000000e: 77 5c 22 0c e1 f5 7b 83 45 85 c0 ed 08 10 w\"...{.E..... 000001c: d3 46 0c 5c 22 59 f8 da 7b f8 18...
View ArticleAnswer by fluffy for Tweetable hash function challenge
C++: 7112 6694 6483 6479 6412 6339 collisions, 90 bytes I implemented a naïve genetic algorithm for my coefficient array. I'll update this code as it finds better ones. :) int h(const char*s){uint32_t...
View ArticleAnswer by Blue for Tweetable hash function challenge
Python, 6995 6862 6732 Just a simple RSA function. Pretty lame, but beats some answers. M=0x5437b3a3b1 P=0x65204c34d def H(s): n=0 for i in range(len(s)): n+=pow(ord(s[i]),P,M)<<i return n%(8**8)
View ArticleAnswer by Anders Kaseorg for Tweetable hash function challenge
Python 2, 140 bytes, 4266 colliding words I didn’t really want to start with the non-printable bytes thing given their unclear tweetability, but well, I didn’t start it. :-P 00000000: efbb bf64 6566...
View ArticleAnswer by jose_castro_arnaud for Tweetable hash function challenge
Ruby, 9309 collisions, 107 bytes def hash(s);require'prime';p=Prime.first(70);(0...s.size).reduce(0){|a,i|a+=p[i]**(s[i].ord)}%(2**24-1);end Not a good contender, but I wanted to explore a different...
View ArticleAnswer by Paul Chernoch for Tweetable hash function challenge
Ruby, 6473 collisions, 129 bytes h=->(w){@p=@p||(2..999).select{|i|(2..i**0.5).select{|j|i%j==0}==[]};c=w.chars.reduce(1){|a,s|(a*@p[s.ord%92]+179)%((1<<24)-3)}} The @p variable is filled with...
View ArticleAnswer by bmm6o for Tweetable hash function challenge
C#, 6251 6335 int H(String s){int h = 733;foreach (char c in s){h = (h * 533 + c);}return h & 0xFFFFFF;} The constants 533 and 733 889 and 155 give the best score out of all of the ones I've...
View ArticleAnswer by kasperd for Tweetable hash function challenge
Python, 5333 4991 I believe this is the first contender to score significantly better than a random oracle. def H(s):n=int(s.encode('hex'),16);return...
View ArticleAnswer by binarymax for Tweetable hash function challenge
Javascript (ES5), 6765 This is CRC24 shaved down to 140 Bytes. Could golf more but wanted to get my answer in :)...
View ArticleAnswer by Dennis for Tweetable hash function challenge
CJam, 6273 {49f^245b16777213%} XOR each character with 49, reduce the resulting string via x, y ↦ 245x + y, and take the residue modulo 16,777,213 (the largest 24-bit prime). Scoring $ cat...
View ArticleAnswer by Godric Seer for Tweetable hash function challenge
Matlab, 30828 8620 6848 It builds the hash by assigning a prime number to each ascii character/position combo and calculating their product for each word modulo the largest prime smaller than 2^24....
View ArticleAnswer by Bewusstsein for Tweetable hash function challenge
Java 8, 7054 6467 This is inspired by (but not copied from) the builtin java.lang.String.hashCode function, so feel free to disallow according to rule #2. w -> { return w.chars().reduce(53, (acc, c)...
View ArticleAnswer by Mwr247 for Tweetable hash function challenge
JavaScript (ES6), 6389 The hash function (105 bytes): s=>[...s.replace(/[A-Z]/g,a=>(b=a.toLowerCase())+b+b)].reduce((a,b)=>(a<<3)*28-a^b.charCodeAt(),0)<<8>>>8 The scoring...
View ArticleAnswer by ASCII-only for Tweetable hash function challenge
Python, 6390 6376 6359 H=lambda s:reduce(lambda a,x:a*178+ord(x),s,0)%(2**24-48) May be considered a trivial modification to Martin Büttner's answer.
View ArticleAnswer by kasperd for Tweetable hash function challenge
Python, 6446 6372 This solution achieves lower collision count than all previous entries, and it needs only 44 of the 140 bytes allowed for code: H=lambda s:int(s.encode('hex'),16)%16727401
View ArticleAnswer by Mr Public for Tweetable hash function challenge
Python, 9310 Yeah, not the best, but at least it is something. As we say in crypto, never write your own hash function. This is exactly 140 bytes long, as well. F=lambda...
View ArticleAnswer by Martin Ender for Tweetable hash function challenge
Mathematica, 6473 The next step up... instead of summing the character codes we treat them as the digits of a base-151 number, before taking them modulo 224. hash[word_] :=...
View ArticleAnswer by orlp for Tweetable hash function challenge
Python, 340053 A terrible score from a terrible algorithm, this answer exists more to give a small Python script that displays scoring. H=lambda s:sum(map(ord, s))%(2**24) To score: hashes = [] with...
View ArticleTweetable hash function challenge
In this code-challenge you will write a hash function in 140 bytes1 or less of source code. The hash function must take an ASCII string as input, and return a 24-bit unsigned integer ([0, 224-1]) as...
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