A Pen by Riley Shaw.

index.slim

canvas#canvas width=400 height=400

Kaprekar-Routine-Depths:-10k.markdown

Kaprekar Routine Depths: 10k

Generates a plot of total cycle depth for the Kaprekar Routine for the range [0, 10k). Also see the heavyweight 1M version here.

A Pen by Riley Shaw on CodePen.

License.

script.js

;(function () {
  function step (cur, prev, i) {
    if (prev[cur]) return i - 1;
    else prev[cur] = true;
    var lo = String(cur).split('').sort();
    var hi = lo.slice().reverse();
    lo = +(lo.join('')); hi = +(hi.join(''));
    return step(hi - lo, prev, i + 1);
  }

  function kaprekar (num) {
    return step(num, {}, 0);
  }

  var ctx = document.getElementById('canvas').getContext('2d');
  var colors = ['rgb(236, 240, 241)', 'rgb(209, 215, 218)', 'rgb(181, 189, 195)', 'rgb(154, 164, 172)', 'rgb(126, 138, 149)', 'rgb(99, 113, 126)', 'rgb(71, 87, 103)', 'rgb(44, 62, 80)'];

  for (var i = 0; i < 10000; i++) {
    ctx.fillStyle = colors[kaprekar(i)];
    ctx.fillRect((i % 100) * 4, Math.floor(i / 100) * 4, 4, 4);
  }
})();

style.sass

body
  background: rgb(44,62,80)

canvas
  position: absolute
  top: 50%
  left: 50%
  margin: -200px