为什么我的解决方案无法找到二叉树的最小深度？ [英] Why won't my solution work to find minimum depth of a binary tree?

问题描述

我不了解我的用于查找二叉树最小深度的解决方案如何不起作用？我在做什么错了？

I don't understand how my solution for finding minimum depth of a binary tree doesn't work? What am I doing wrong?

如果您好奇的话，这里是问题的链接： https://leetcode.com/problems/minimum-depth-of-binary-tree/submissions/

Here's a link to the problem if you're curious: https://leetcode.com/problems/minimum-depth-of-binary-tree/submissions/

public int minDepth(TreeNode root) {
    if(root == null) return 0;

    int left = minDepth(root.left);
    int right = minDepth(root.right);

    int ans = Math.min(left, right) + 1;

    return ans;
}

推荐答案

您的代码将无法在如果只有一侧是 null ，例如

Your code will not work in the case only one side is null, like

  3
 / \
   20
  /  \
 15   7

因为它将返回1 （而 3 不是叶子）。

as it will return 1 (while 3 is not a leaf).

您需要测试一侧是否为 null ，忽略它并与另一边打交道

You need to test if one side is null, ignore it and deal with the other side

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