// 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));

const permutations = arr => {
  if (arr.length <= 2) return arr.length === 2 ? [arr, [arr[1], arr[0]]] : arr;
  return arr.reduce(
    (acc, item, i) =>
      acc.concat(
        permutations([...arr.slice(0, i), ...arr.slice(i + 1)]).map(val => [
          item,
          ...val,
        ])
      ),
    []
  );
};
permutations([1, 33, 5]);
// [ [1, 33, 5], [1, 5, 33], [33, 1, 5], [33, 5, 1], [5, 1, 33], [5, 33, 1] ]

const jwt = require("jsonwebtoken");

const authToken = (req, res, next) => {
	const token = req.headers["x-auth-token"];

	try {
	req.user = jwt.verify(token, process.env.ACCESS_TOKEN_SECRET);

	next();
	} catch (err) {
	console.log(err.message);
	res.status(401).json({ msg: "Error authenticating token" });
	}
};

module.exports = authToken;

function printHeap(heap, index, level) {
    if (index >= heap.length) {
        return;
    }
    console.log("  ".repeat(level) + heap[index]);
    printHeap(heap, 2 * index + 1, level + 1);
    printHeap(heap, 2 * index + 2, level + 1);
}

//You can call this function by passing in the heap array and the index of the root node, which is typically 0, and level = 0.

let heap = [3, 8, 7, 15, 17, 30, 35, 2, 4, 5, 9];
printHeap(heap,0,0)

const heapsort = arr => {
  const a = [...arr];
  let l = a.length;

  const heapify = (a, i) => {
    const left = 2 * i + 1;
    const right = 2 * i + 2;
    let max = i;
    if (left < l && a[left] > a[max]) max = left;
    if (right < l && a[right] > a[max]) max = right;
    if (max !== i) {
      [a[max], a[i]] = [a[i], a[max]];
      heapify(a, max);
    }
  };

  for (let i = Math.floor(l / 2); i >= 0; i -= 1) heapify(a, i);
  for (i = a.length - 1; i > 0; i--) {
    [a[0], a[i]] = [a[i], a[0]];
    l--;
    heapify(a, 0);
  }
  return a;
};

heapsort([6, 3, 4, 1]); // [1, 3, 4, 6]

// Or
const randomColor = () => `#${(~~(Math.random()*(1<<24))).toString(16)}`;
console.log(randomColor);