const quickSort = arr => {
  const a = [...arr];
  if (a.length < 2) return a;
  const pivotIndex = Math.floor(arr.length / 2);
  const pivot = a[pivotIndex];
  const [lo, hi] = a.reduce(
    (acc, val, i) => {
      if (val < pivot || (val === pivot && i != pivotIndex)) {
        acc[0].push(val);
      } else if (val > pivot) {
        acc[1].push(val);
      }
      return acc;
    },
    [[], []]
  );
  return [...quickSort(lo), pivot, ...quickSort(hi)];
};

console.log(quickSort([1, 6, 1, 5, 3, 2, 1, 4])) // [1, 1, 1, 2, 3, 4, 5, 6]

import React, { useState, useEffect } from 'react';
import Link from 'next/link';

export default function CookieBanner() {
    // Initialize with a default value (false if not previously set in localStorage)
  const [cookieConsent, setCookieConsent] = useState(() =>
    localStorage.getItem('cookieConsent') === 'true' ? true : false
  );

  useEffect(() => {
    const newCookieConsent = cookieConsent ? 'granted' : 'denied';

    window.gtag('consent', 'update', {
      analytics_storage: newCookieConsent
    });

    localStorage.setItem('cookieConsent', String(cookieConsent));
  }, [cookieConsent]);

  return !cookieConsent && (
    <div>
    <div>
        <p>
        We use cookies to enhance the user experience.{' '}
        <Link href='/privacy/'>View privacy policy</Link>
        </p>
    </div>
    <div>
        <button type="button" onClick={() => setCookieConsent(false)}>Decline</button>
        <button type="button" onClick={() => setCookieConsent(true)}>Allow</button>
    </div>
    </div>
  )
}

// promisify(f, true) to get array of results
function promisify(f, manyArgs = false) {
  return function (...args) {
    return new Promise((resolve, reject) => {
      function callback(err, ...results) { // our custom callback for f
        if (err) {
          reject(err);
        } else {
          // resolve with all callback results if manyArgs is specified
          resolve(manyArgs ? results : results[0]);
        }
      }

      args.push(callback);

      f.call(this, ...args);
    });
  };
}

// usage:
f = promisify(f, true);
f(...).then(arrayOfResults => ..., err => ...);

var invertTree = function(root) {
    const reverseNode = node => {
        if (node == null) {
            return null
        }
        reverseNode(node.left);
        reverseNode(node.right);
        let holdLeft = node.left;
        node.left = node.right;
        node.right = holdLeft;
        return node;
    }

    return reverseNode(root);
};

const toFixed = (n, fixed) => ~~(Math.pow(10, fixed) * n) / Math.pow(10, fixed);
// Examples
toFixed(25.198726354, 1);       // 25.1
toFixed(25.198726354, 2);       // 25.19
toFixed(25.198726354, 3);       // 25.198
toFixed(25.198726354, 4);       // 25.1987
toFixed(25.198726354, 5);       // 25.19872
toFixed(25.198726354, 6);       // 25.198726

const unzipWith = (arr, fn) =>
  arr
    .reduce(
      (acc, val) => (val.forEach((v, i) => acc[i].push(v)), acc),
      Array.from({
        length: Math.max(...arr.map(x => x.length))
      }).map(x => [])
    )
    .map(val => fn(...val));
unzipWith(
  [
    [1, 10, 100],
    [2, 20, 200],
  ],
  (...args) => args.reduce((acc, v) => acc + v, 0)
);
// [3, 30, 300]