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44 lines
1.7 KiB
HTML
<p>You are given the <code>root</code> of a binary tree with <strong>unique</strong> values, and an integer <code>start</code>. At minute <code>0</code>, an <strong>infection</strong> starts from the node with value <code>start</code>.</p>
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<p>Each minute, a node becomes infected if:</p>
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<ul>
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<li>The node is currently uninfected.</li>
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<li>The node is adjacent to an infected node.</li>
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</ul>
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<p>Return <em>the number of minutes needed for the entire tree to be infected.</em></p>
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<p> </p>
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<p><strong>Example 1:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2022/06/25/image-20220625231744-1.png" style="width: 400px; height: 306px;" />
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<pre>
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<strong>Input:</strong> root = [1,5,3,null,4,10,6,9,2], start = 3
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<strong>Output:</strong> 4
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<strong>Explanation:</strong> The following nodes are infected during:
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- Minute 0: Node 3
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- Minute 1: Nodes 1, 10 and 6
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- Minute 2: Node 5
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- Minute 3: Node 4
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- Minute 4: Nodes 9 and 2
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It takes 4 minutes for the whole tree to be infected so we return 4.
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</pre>
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<p><strong>Example 2:</strong></p>
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<img alt="" src="https://assets.leetcode.com/uploads/2022/06/25/image-20220625231812-2.png" style="width: 75px; height: 66px;" />
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<pre>
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<strong>Input:</strong> root = [1], start = 1
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<strong>Output:</strong> 0
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<strong>Explanation:</strong> At minute 0, the only node in the tree is infected so we return 0.
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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>The number of nodes in the tree is in the range <code>[1, 10<sup>5</sup>]</code>.</li>
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<li><code>1 <= Node.val <= 10<sup>5</sup></code></li>
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<li>Each node has a <strong>unique</strong> value.</li>
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<li>A node with a value of <code>start</code> exists in the tree.</li>
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</ul>
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