HailStoneSequence Solution

Contributors
1

What is your hint or solution suggestion?

function hailstoneSequence() {
  var res = [], n =27, c1 = [],  c2 = [351,77031];
/*You already know c2 from Wikipedia page, and its max arr
 length... Please don't make the poor machine do it again... */

  c1.push(n);
  /*While Res Loop Collatz 1*/

  while(n != 1){
   n = (n%2== 0) ? (n/2): (3*n + 1);
   c1.push(n);

  }//End of c1

  var newC1 = [c1[0], c1[1], c1[2], c1[3],
 c1[c1.length-4], c1[c1.length-3], c1[c1.length-2],
 c1[c1.length-1] ];
 
c1 = newC1;
 
console.log(`The final c1 matrix before c2 data is ${c1}.\n`);
 
 res.push(c1);
  res.push(c2);
 
 console.log(`Final Collatz result matrix is ${res}.\n`);
  return res; 
} /*My 1st Ancient Egyptian Spoiler Tag... Sorry*/

Challenge: Hailstone sequence

Link to the challenge:

2

Hey @mlpfanatic903!

So I was corrected that for the guide submissions to use the [details][/details] tags.

So that was my bad. Sorry.

You are doing great with these rosetta problems. Keep up the great work. I just finished the 100 doors challenge.

Happy coding!

3

Thanks… Same to you. I’ve explored the ideas behind the 100 doors challenge, and the map versions seem to run the best for whatever reason…

4

I have a couple of issues with that solution, it uses old (var) syntax, and it doesn’t really follow the instructions (which suggest to write a helper function to get the hailStone sequence for any given number). This function could then be re-used to calculate the solution for the second task, instead of hardcoding it.

function hailstoneSequence() {
  const res = [];

  /* 1.: Create a routine to generate the hailstone sequence for a number */
  const hailStones = n => {
    let result = [n];
    while (n > 1){
      n = n%2 === 0 ? n/2 : 3*n+1;
      result.push(n)
    };
    return result;
  }

  /* 2.: Hailstone sequence for n=27 */
  let n = 27;
  const seq1 = hailStones(n);
  const res1 = [...seq1.slice(0,4), ...seq1.slice(-4)];
  res.push(res1);

  /* 3.: Hailstone sequence for n=77031 */
  n = 77031;
  const seq2 = hailStones(n);
  const res2 = [seq2.length, n];
  res.push(res2);
  
  return res;
}
5

So we can agree on the method of implementation, but not on the intrinsic code that does the same function… Interesting Q… To each their own, I guess…
Nice touch with the .slice() method btw.

6

I just thought that when someone looks up the hints for the second task, and all he finds is a hardcoded array [351,77031], it could be a little disappointing. They may wonder why the challenge includes that second task at all.

7

Thank you for your guide post contribution. I have taken your suggestions and included the combination in the guide post.

We look forward to your further contribution.

1 Like