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41 lines
2.2 KiB
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41 lines
2.2 KiB
HTML
<p>You are given a 2D integer array <code>descriptions</code> where <code>descriptions[i] = [parent<sub>i</sub>, child<sub>i</sub>, isLeft<sub>i</sub>]</code> indicates that <code>parent<sub>i</sub></code> is the <strong>parent</strong> of <code>child<sub>i</sub></code> in a <strong>binary</strong> tree of <strong>unique</strong> values. Furthermore,</p>
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<ul>
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<li>If <code>isLeft<sub>i</sub> == 1</code>, then <code>child<sub>i</sub></code> is the left child of <code>parent<sub>i</sub></code>.</li>
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<li>If <code>isLeft<sub>i</sub> == 0</code>, then <code>child<sub>i</sub></code> is the right child of <code>parent<sub>i</sub></code>.</li>
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</ul>
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<p>Construct the binary tree described by <code>descriptions</code> and return <em>its <strong>root</strong></em>.</p>
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<p>The test cases will be generated such that the binary tree is <strong>valid</strong>.</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/2022/02/09/example1drawio.png" style="width: 300px; height: 236px;" />
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<pre>
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<strong>Input:</strong> descriptions = [[20,15,1],[20,17,0],[50,20,1],[50,80,0],[80,19,1]]
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<strong>Output:</strong> [50,20,80,15,17,19]
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<strong>Explanation:</strong> The root node is the node with value 50 since it has no parent.
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The resulting binary tree is shown in the diagram.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2022/02/09/example2drawio.png" style="width: 131px; height: 300px;" />
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<pre>
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<strong>Input:</strong> descriptions = [[1,2,1],[2,3,0],[3,4,1]]
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<strong>Output:</strong> [1,2,null,null,3,4]
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<strong>Explanation:</strong> The root node is the node with value 1 since it has no parent.
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The resulting binary tree is shown in the diagram.
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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 <= descriptions.length <= 10<sup>4</sup></code></li>
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<li><code>descriptions[i].length == 3</code></li>
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<li><code>1 <= parent<sub>i</sub>, child<sub>i</sub> <= 10<sup>5</sup></code></li>
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<li><code>0 <= isLeft<sub>i</sub> <= 1</code></li>
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<li>The binary tree described by <code>descriptions</code> is valid.</li>
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</ul>
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