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52 lines
2.3 KiB
HTML
52 lines
2.3 KiB
HTML
<p>You are given the <code>root</code> of a binary tree with <strong>unique values</strong>.</p>
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<p>In one operation, you can choose any two nodes <strong>at the same level</strong> and swap their values.</p>
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<p>Return <em>the minimum number of operations needed to make the values at each level sorted in a <strong>strictly increasing order</strong></em>.</p>
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<p>The <strong>level</strong> of a node is the number of edges along the path between it and the root node<em>.</em></p>
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<p> </p>
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<p><strong class="example">Example 1:</strong></p>
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<img src="https://assets.leetcode.com/uploads/2022/09/18/image-20220918174006-2.png" style="width: 500px; height: 324px;" />
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<pre>
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<strong>Input:</strong> root = [1,4,3,7,6,8,5,null,null,null,null,9,null,10]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong>
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- Swap 4 and 3. The 2<sup>nd</sup> level becomes [3,4].
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- Swap 7 and 5. The 3<sup>rd</sup> level becomes [5,6,8,7].
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- Swap 8 and 7. The 3<sup>rd</sup> level becomes [5,6,7,8].
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We used 3 operations so return 3.
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It can be proven that 3 is the minimum number of operations needed.
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</pre>
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<p><strong class="example">Example 2:</strong></p>
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<img src="https://assets.leetcode.com/uploads/2022/09/18/image-20220918174026-3.png" style="width: 400px; height: 303px;" />
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<pre>
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<strong>Input:</strong> root = [1,3,2,7,6,5,4]
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<strong>Output:</strong> 3
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<strong>Explanation:</strong>
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- Swap 3 and 2. The 2<sup>nd</sup> level becomes [2,3].
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- Swap 7 and 4. The 3<sup>rd</sup> level becomes [4,6,5,7].
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- Swap 6 and 5. The 3<sup>rd</sup> level becomes [4,5,6,7].
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We used 3 operations so return 3.
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It can be proven that 3 is the minimum number of operations needed.
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</pre>
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<p><strong class="example">Example 3:</strong></p>
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<img src="https://assets.leetcode.com/uploads/2022/09/18/image-20220918174052-4.png" style="width: 400px; height: 274px;" />
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<pre>
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<strong>Input:</strong> root = [1,2,3,4,5,6]
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<strong>Output:</strong> 0
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<strong>Explanation:</strong> Each level is already sorted in increasing order so 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>All the values of the tree are <strong>unique</strong>.</li>
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</ul>
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