const gcd = (...arr) => {
  const _gcd = (x, y) => (!y ? x : gcd(y, x % y));
  return [...arr].reduce((a, b) => _gcd(a, b));
};

gcd(8, 36); // 4
gcd(...[12, 8, 32]); // 4

const copyToClipboard = str => {
  const el = document.createElement('textarea');
  el.value = str;
  el.setAttribute('readonly', '');
  el.style.position = 'absolute';
  el.style.left = '-9999px';
  document.body.appendChild(el);
  const selected =
    document.getSelection().rangeCount > 0
      ? document.getSelection().getRangeAt(0)
      : false;
  el.select();
  document.execCommand('copy');
  document.body.removeChild(el);
  if (selected) {
    document.getSelection().removeAllRanges();
    document.getSelection().addRange(selected);
  }
};

copyToClipboard('Lorem ipsum'); // 'Lorem ipsum' copied to clipboard.

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

// Time Complexity : O(N)
// Space Complexity : O(1)
 
var isMonotonic = function(nums) {
    let isMono = null;
    for(let i = 1; i < nums.length; i++) {
        if(isMono === null) {
            if(nums[i - 1] < nums[i]) isMono = 0;
            else if(nums[i - 1] > nums[i]) isMono = 1;
            continue;
        }
        if(nums[i - 1] < nums[i] && isMono !== 0) {
            return false;
        }
        else if(nums[i - 1] > nums[i] && isMono !== 1) {
            return false;
        }
    }
    
    return true;
    
};

let nums1 = [1,2,2,3]
let nums2 = [6,5,4,4]
let nums3 = [1,3,2]

console.log(isMonotonic(nums1));
console.log(isMonotonic(nums2));
console.log(isMonotonic(nums3));

/**
 * @param {number[]} nums
 * @return {boolean}
 */
var containsDuplicate = function(nums) {
    return new Set(nums).size !== nums.length
};