Monotonic Array
<p>An array is <strong>monotonic</strong> if it is either monotone increasing or monotone decreasing.</p>

<p>An array <code>nums</code> is monotone increasing if for all <code>i &lt;= j</code>, <code>nums[i] &lt;= nums[j]</code>. An array <code>nums</code> is monotone decreasing if for all <code>i &lt;= j</code>, <code>nums[i] &gt;= nums[j]</code>.</p>

<p>Given an integer array <code>nums</code>, return <code>true</code><em> if the given array is monotonic, or </em><code>false</code><em> otherwise</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,2,2,3]
<strong>Output:</strong> true
</pre>

<p><strong class="example">Example 2:</strong></p>

<pre>
<strong>Input:</strong> nums = [6,5,4,4]
<strong>Output:</strong> true
</pre>

<p><strong class="example">Example 3:</strong></p>

<pre>
<strong>Input:</strong> nums = [1,3,2]
<strong>Output:</strong> false
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= nums.length &lt;= 10<sup>5</sup></code></li>
	<li><code>-10<sup>5</sup> &lt;= nums[i] &lt;= 10<sup>5</sup></code></li>
</ul>
Array
/**
 * @param {number[]} nums
 * @return {boolean}
 */
var isMonotonic = function (nums) {
    let [asc, desc] = [false, false];
    for (let i = 1; i < nums.length; ++i) {
        if (nums[i - 1] < nums[i]) {
            asc = true;
        } else if (nums[i - 1] > nums[i]) {
            desc = true;
        }
        if (asc && desc) {
            return false;
        }
    }
    return true;
};
