<p>Given an array of integers <code>arr</code>, return <em><code>true</code> if and only if it is a valid mountain array</em>.</p>

<p>Recall that arr is a mountain array if and only if:</p>

<ul>
	<li><code>arr.length &gt;= 3</code></li>
	<li>There exists some <code>i</code> with <code>0 &lt; i &lt; arr.length - 1</code> such that:
	<ul>
		<li><code>arr[0] &lt; arr[1] &lt; ... &lt; arr[i - 1] &lt; arr[i] </code></li>
		<li><code>arr[i] &gt; arr[i + 1] &gt; ... &gt; arr[arr.length - 1]</code></li>
	</ul>
	</li>
</ul>
<img src="https://assets.leetcode.com/uploads/2019/10/20/hint_valid_mountain_array.png" width="500" />
<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<pre><strong>Input:</strong> arr = [2,1]
<strong>Output:</strong> false
</pre><p><strong class="example">Example 2:</strong></p>
<pre><strong>Input:</strong> arr = [3,5,5]
<strong>Output:</strong> false
</pre><p><strong class="example">Example 3:</strong></p>
<pre><strong>Input:</strong> arr = [0,3,2,1]
<strong>Output:</strong> true
</pre>
<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>1 &lt;= arr.length &lt;= 10<sup>4</sup></code></li>
	<li><code>0 &lt;= arr[i] &lt;= 10<sup>4</sup></code></li>
</ul>

class Solution:
    def validMountainArray(self, arr: List[int]) -> bool:
        if len(arr)<3:
            return False
        runner = 1
        left_flag = right_flag = False
        while runner < len(arr) -1:
            if arr[runner-1] < arr[runner]:
                runner += 1
                left_flag = True
            else:
                break
        runner -= 1
        print(runner)
        while runner < len(arr)-1:
            if arr[runner]<=arr[runner+1]:
                return False
            runner +=1
            right_flag = True
            
        return True and right_flag and left_flag
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