CS-Notes/notes/26. 树的子结构.md

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2019-11-02 12:07:41 +08:00
# 26. 树的子结构
[NowCoder](https://www.nowcoder.com/practice/6e196c44c7004d15b1610b9afca8bd88?tpId=13&tqId=11170&tPage=1&rp=1&ru=/ta/coding-interviews&qru=/ta/coding-interviews/question-ranking&from=cyc_github)
## 题目描述
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<div align="center"> <img src="pics/84a5b15a-86c5-4d8e-9439-d9fd5a4699a1.jpg" width="450"/> </div><br>
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## 解题思路
```java
public boolean HasSubtree(TreeNode root1, TreeNode root2) {
if (root1 == null || root2 == null)
return false;
return isSubtreeWithRoot(root1, root2) || HasSubtree(root1.left, root2) || HasSubtree(root1.right, root2);
}
private boolean isSubtreeWithRoot(TreeNode root1, TreeNode root2) {
if (root2 == null)
return true;
if (root1 == null)
return false;
if (root1.val != root2.val)
return false;
return isSubtreeWithRoot(root1.left, root2.left) && isSubtreeWithRoot(root1.right, root2.right);
}
```
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