最小高度树Java版本（力扣）

最新推荐文章于 2025-04-21 22:09:55 发布

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最新推荐文章于 2025-04-21 22:09:55 发布

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原文链接：https://blog.youkuaiyun.com/weixin_43883917/article/details/112121618?utm_medium=distribute.pc_category.none-task-blog-hot-11.nonecase&depth_1-utm_source=distribute.pc_category.none-task-blog-hot-11.nonecase

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最小高度树

给定一个有序整数数组，元素各不相同且按升序排列，编写一个算法，创建一棵高度最小的二叉搜索树。

示例:
给定有序数组: [-10,-3,0,5,9],
一个可能的答案是：[0,-3,9,-10,null,5]，它可以表示下面这个高度平衡二叉搜索树：

<span style="color:#000000"><code>      0 
     / \ 
   -3   9 
   /   / 
 -10  5 
</code></span>

题意：让我们根据给的有序数组，创建一个高度最小的二叉树。

思路：递归求解，sortedArrayToBST方法中传入的数组，我们取数组的中间值为根节点，然后将数组的左半部分传入sortedArrayToBST方法，这样返回的就是左子树的根节点，赋值给node.left ；将数组的右半部分传入sortedArrayToBST方法，这样返回的就是右子树的根节点，赋值给node.right ，就这样一直递归下去，最后机就构建成了一棵高度最小的二叉搜索树。

正确代码：

<span style="color:#000000"><code class="language-java"><span style="color:#c678dd">class</span> Solution <span style="color:#999999">{</span>
    <span style="color:#c678dd">public</span> TreeNode <span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span><span style="color:#c678dd">int</span><span style="color:#999999">[</span><span style="color:#999999">]</span> nums<span style="color:#999999">)</span> <span style="color:#999999">{</span>
        <span style="color:#c678dd">if</span><span style="color:#999999">(</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">==</span><span style="color:#98c379">0</span><span style="color:#999999">)</span>
        <span style="color:#c678dd">return</span> null<span style="color:#999999">;</span>
        TreeNode node <span style="color:#669900">=</span> <span style="color:#c678dd">new</span> TreeNode<span style="color:#999999">(</span>nums<span style="color:#999999">[</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">/</span><span style="color:#98c379">2</span><span style="color:#999999">]</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        node<span style="color:#999999">.</span>left <span style="color:#669900">=</span> <span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span>Arrays<span style="color:#999999">.</span><span style="color:#61aeee">copyOfRange</span><span style="color:#999999">(</span>nums<span style="color:#999999">,</span><span style="color:#98c379">0</span><span style="color:#999999">,</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">/</span><span style="color:#98c379">2</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        node<span style="color:#999999">.</span>right <span style="color:#669900">=</span> <span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span>Arrays<span style="color:#999999">.</span><span style="color:#61aeee">copyOfRange</span><span style="color:#999999">(</span>nums<span style="color:#999999">,</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">/</span><span style="color:#98c379">2</span><span style="color:#669900">+</span><span style="color:#98c379">1</span><span style="color:#999999">,</span>nums<span style="color:#999999">.</span>length<span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        <span style="color:#c678dd">return</span> node<span style="color:#999999">;</span>
    <span style="color:#999999">}</span>
<span style="color:#999999">}</span>
</code></span>

完整代码（含测试代码）：

<span style="color:#000000"><code class="language-java"><span style="color:#c678dd">package</span> com<span style="color:#999999">.</span>Keafmd<span style="color:#999999">.</span>day0102<span style="color:#999999">;</span>

<span style="color:#c678dd">import</span> java<span style="color:#999999">.</span>util<span style="color:#999999">.</span>Arrays<span style="color:#999999">;</span>

<span style="color:#5c6370">/**
 * Keafmd
 *
 * @ClassName: MinimumHeightTree
 * @Description: 最小高度树
 * @author: 牛哄哄的柯南
 * @date: 2021-01-02 19:29
 */</span>
<span style="color:#c678dd">public</span> <span style="color:#c678dd">class</span> MinimumHeightTree <span style="color:#999999">{</span>
    <span style="color:#c678dd">public</span> <span style="color:#c678dd">static</span> <span style="color:#c678dd">void</span> <span style="color:#61aeee">main</span><span style="color:#999999">(</span>String<span style="color:#999999">[</span><span style="color:#999999">]</span> args<span style="color:#999999">)</span> <span style="color:#999999">{</span>

        Solution01022 solution01022 <span style="color:#669900">=</span> <span style="color:#c678dd">new</span> Solution01022<span style="color:#999999">(</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        <span style="color:#c678dd">int</span> <span style="color:#999999">[</span><span style="color:#999999">]</span>nums<span style="color:#669900">=</span><span style="color:#999999">{</span><span style="color:#669900">-</span><span style="color:#98c379">10</span><span style="color:#999999">,</span><span style="color:#669900">-</span><span style="color:#98c379">3</span><span style="color:#999999">,</span><span style="color:#98c379">0</span><span style="color:#999999">,</span><span style="color:#98c379">5</span><span style="color:#999999">,</span><span style="color:#98c379">9</span><span style="color:#999999">}</span><span style="color:#999999">;</span>
        TreeNode result <span style="color:#669900">=</span> solution01022<span style="color:#999999">.</span><span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span>nums<span style="color:#999999">)</span><span style="color:#999999">;</span>
        System<span style="color:#999999">.</span>out<span style="color:#999999">.</span><span style="color:#61aeee">println</span><span style="color:#999999">(</span>result<span style="color:#999999">.</span>val<span style="color:#999999">)</span><span style="color:#999999">;</span>
        System<span style="color:#999999">.</span>out<span style="color:#999999">.</span><span style="color:#61aeee">println</span><span style="color:#999999">(</span>result<span style="color:#999999">.</span>left<span style="color:#999999">.</span>val<span style="color:#999999">)</span><span style="color:#999999">;</span>
        System<span style="color:#999999">.</span>out<span style="color:#999999">.</span><span style="color:#61aeee">println</span><span style="color:#999999">(</span>result<span style="color:#999999">.</span>right<span style="color:#999999">.</span>val<span style="color:#999999">)</span><span style="color:#999999">;</span>
    <span style="color:#999999">}</span>
<span style="color:#999999">}</span>
<span style="color:#c678dd">class</span> TreeNode <span style="color:#999999">{</span>
      <span style="color:#c678dd">int</span> val<span style="color:#999999">;</span>
      TreeNode left<span style="color:#999999">;</span>
      TreeNode right<span style="color:#999999">;</span>
      <span style="color:#61aeee">TreeNode</span><span style="color:#999999">(</span><span style="color:#c678dd">int</span> x<span style="color:#999999">)</span> <span style="color:#999999">{</span> val <span style="color:#669900">=</span> x<span style="color:#999999">;</span> <span style="color:#999999">}</span>
<span style="color:#999999">}</span>
<span style="color:#c678dd">class</span> Solution01022 <span style="color:#999999">{</span>
    <span style="color:#c678dd">public</span> TreeNode <span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span><span style="color:#c678dd">int</span><span style="color:#999999">[</span><span style="color:#999999">]</span> nums<span style="color:#999999">)</span> <span style="color:#999999">{</span>
        <span style="color:#c678dd">if</span><span style="color:#999999">(</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">==</span><span style="color:#98c379">0</span><span style="color:#999999">)</span>
        <span style="color:#c678dd">return</span> null<span style="color:#999999">;</span>
        TreeNode node <span style="color:#669900">=</span> <span style="color:#c678dd">new</span> TreeNode<span style="color:#999999">(</span>nums<span style="color:#999999">[</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">/</span><span style="color:#98c379">2</span><span style="color:#999999">]</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        node<span style="color:#999999">.</span>left <span style="color:#669900">=</span> <span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span>Arrays<span style="color:#999999">.</span><span style="color:#61aeee">copyOfRange</span><span style="color:#999999">(</span>nums<span style="color:#999999">,</span><span style="color:#98c379">0</span><span style="color:#999999">,</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">/</span><span style="color:#98c379">2</span><span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        node<span style="color:#999999">.</span>right <span style="color:#669900">=</span> <span style="color:#61aeee">sortedArrayToBST</span><span style="color:#999999">(</span>Arrays<span style="color:#999999">.</span><span style="color:#61aeee">copyOfRange</span><span style="color:#999999">(</span>nums<span style="color:#999999">,</span>nums<span style="color:#999999">.</span>length<span style="color:#669900">/</span><span style="color:#98c379">2</span><span style="color:#669900">+</span><span style="color:#98c379">1</span><span style="color:#999999">,</span>nums<span style="color:#999999">.</span>length<span style="color:#999999">)</span><span style="color:#999999">)</span><span style="color:#999999">;</span>
        <span style="color:#c678dd">return</span> node<span style="color:#999999">;</span>
    <span style="color:#999999">}</span>
<span style="color:#999999">}</span>

</code></span>

输出结果：

<span style="color:#000000"><code class="language-java"><span style="color:#98c379">0</span>
<span style="color:#669900">-</span><span style="color:#98c379">3</span>
<span style="color:#98c379">9</span>

Process finished with exit code <span style="color:#98c379">0</span>
</code></span>

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