Class Solution
java.lang.Object
g1001_1100.s1028_recover_a_tree_from_preorder_traversal.Solution
1028 - Recover a Tree From Preorder Traversal.<p>Hard</p>
<p>We run a preorder depth-first search (DFS) on the <code>root</code> of a binary tree.</p>
<p>At each node in this traversal, we output <code>D</code> dashes (where <code>D</code> is the depth of this node), then we output the value of this node. If the depth of a node is <code>D</code>, the depth of its immediate child is <code>D + 1</code>. The depth of the <code>root</code> node is <code>0</code>.</p>
<p>If a node has only one child, that child is guaranteed to be <strong>the left child</strong>.</p>
<p>Given the output <code>traversal</code> of this traversal, recover the tree and return <em>its</em> <code>root</code>.</p>
<p><strong>Example 1:</strong></p>
<p><img src="https://assets.leetcode.com/uploads/2019/04/08/recover-a-tree-from-preorder-traversal.png" alt="" /></p>
<p><strong>Input:</strong> traversal = “1-2–3–4-5–6–7”</p>
<p><strong>Output:</strong> [1,2,5,3,4,6,7]</p>
<p><strong>Example 2:</strong></p>
<p><img src="https://assets.leetcode.com/uploads/2019/04/11/screen-shot-2019-04-10-at-114101-pm.png" alt="" /></p>
<p><strong>Input:</strong> traversal = “1-2–3—4-5–6—7”</p>
<p><strong>Output:</strong> [1,2,5,3,null,6,null,4,null,7]</p>
<p><strong>Example 3:</strong></p>
<p><img src="https://assets.leetcode.com/uploads/2019/04/11/screen-shot-2019-04-10-at-114955-pm.png" alt="" /></p>
<p><strong>Input:</strong> traversal = “1-401–349—90–88”</p>
<p><strong>Output:</strong> [1,401,null,349,88,90]</p>
<p><strong>Constraints:</strong></p>
<ul>
<li>The number of nodes in the original tree is in the range <code>[1, 1000]</code>.</li>
<li><code>1 <= Node.val <= 10<sup>9</sup></code></li>
</ul>
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Constructor Summary
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Solution
public Solution()
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Method Details
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recoverFromPreorder
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