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32 lines
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32 lines
1.5 KiB
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<p>Given an array of integers preorder, which represents the <strong>preorder traversal</strong> of a BST (i.e., <strong>binary search tree</strong>), construct the tree and return <em>its root</em>.</p>
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<p>It is <strong>guaranteed</strong> that there is always possible to find a binary search tree with the given requirements for the given test cases.</p>
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<p>A <strong>binary search tree</strong> is a binary tree where for every node, any descendant of <code>Node.left</code> has a value <strong>strictly less than</strong> <code>Node.val</code>, and any descendant of <code>Node.right</code> has a value <strong>strictly greater than</strong> <code>Node.val</code>.</p>
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<p>A <strong>preorder traversal</strong> of a binary tree displays the value of the node first, then traverses <code>Node.left</code>, then traverses <code>Node.right</code>.</p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2019/03/06/1266.png" style="height: 386px; width: 590px;" />
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<pre>
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<strong>Input:</strong> preorder = [8,5,1,7,10,12]
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<strong>Output:</strong> [8,5,10,1,7,null,12]
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<pre>
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<strong>Input:</strong> preorder = [1,3]
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<strong>Output:</strong> [1,null,3]
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</pre>
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<p> </p>
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<p><strong>Constraints:</strong></p>
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<ul>
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<li><code>1 <= preorder.length <= 100</code></li>
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<li><code>1 <= preorder[i] <= 1000</code></li>
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<li>All the values of <code>preorder</code> are <strong>unique</strong>.</li>
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</ul>
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