CODEWITHSUNDEEP
javascriptstringalgorithmmathhash
user3596335
user3596335

Reputation:

Develop own "Hash" algorithm

So I got a integer variable between 1 and 10,000.

I'd like to convert every number to a unique! hash value that has a fixed length and has a custom charset (includes all alphabetic lowercase and uppercase characters).

So:

I do not really know how to develop an algorithm like this so this is all I got so far. I think the algorithm should work but of course I get a integer value as hash - not a alphabetic value. No idea how to fix this and how to pad the result to give it a fixed length.

I really hope somebody is able to help me.

let value = "3325";


var getHash = function(value) {
  let hash = 0;
  for (let i = 0; i < value.length; i++) {
    let char = value.charCodeAt(i);
    hash = (hash << 6) + char + (char << 14);
    hash=-hash
  } return hash;
};

console.log(getHash(value))

Upvotes: 0

Views: 333

Answers (1)

גלעד ברקן
גלעד ברקן

Reputation: 23955

Here's a hash function that seems to do what you are asking for :) As a bonus, it offers no collisions til 100,000.

function h(n){
  let s = [
    '0101000', '1011010', '0011111',
    '1100001', '1100101', '1011001',
    '1110011', '1010101', '1000111',
    '0001100', '1001000'].map(x => parseInt(x, 2));
    
  let m = parseInt('101', 2);
  
  s = s.map(x => {
    n ^= m;
    m <<= 1;
    return (x ^ n) % 52;
  });

  return s.map(x =>
    String.fromCharCode(x > 25 ? 71 + x : 65 + x)
  ).join('');
}

const s = {};

for (let j=1; j <=10000; j++){
  let hash = h(j);
  
  if (s[hash])
    console.log('Collision! ' + j + ' <-> ' + s[hash]);
    
  s[hash] = j;
}

console.log('Done. No collisions below 10000.');

for (let j=1; j <11; j++)
  console.log(j, h(j));

Upvotes: 2

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