ghtr54t36y45u6jyh.js

const getPrev = (n, list) => (n > 0 ? n - 1 : list.length - 1);

function shake(input) {
  const result = input.slice(0);

  let debug_CyclesCount = 0;

  result.forEach((el, i) => {
    const next = result[i + 1];
    if (el !== next) return;

    let iTarget = i;
    while (true) {
      iTarget = getPrev(iTarget, result);

      if (iTarget === i) throw new Error("We're stuck here :)");

      const iTargetBorder = getPrev(iTarget, result);
      const target = result[iTarget];
      if (
        target !== el &&
        result[iTargetBorder] !== el &&
        result[iTarget + 1] !== el
      ) {
        debug_CyclesCount++;
        result[iTarget] = el;
        result[i] = target;
        break;
      }
    }
  });

  const count = input.length
  const countSet = new Set(input).size

  console.log(
    { input: input.toString(), result: result.toString() },
    `For ~random elements distribution, where ${count} elements and ` +
      `${countSet} unique elements, the number of reordering is: ` +
      debug_CyclesCount
  );
}

shake([1, 1, 2, 3, 4, 5, 5, 5, 5, 6, 7, 8, 7, 9, 10]);
shake([1, 1, 2, 3, 2, 5, 5, 5, 5, 2, 7, 8, 2, 9, 2]);
shake([1, 1, 2, 3, 2, 5, 5, 5]);
shake([1, 1, 2, 3, 2, 5, 5, 5].join('').repeat(3).split(''));