Update 二叉树相关.md

blogs/Algorithm/剑指 Offer/二叉树相关.md

@@ -65,3 +65,27 @@ class Solution {
 }
 ```
 
+#### [26. 树的子结构](https://leetcode-cn.com/problems/shu-de-zi-jie-gou-lcof/)
+
+```java
+class Solution {
+
+    public boolean isSubStructure(TreeNode A, TreeNode B) {
+        if (A == null || B == null) {
+            return false;
+        }
+        return isEquals(A, B) || isSubStructure(A.left, B) || isSubStructure(A.right, B);
+    }
+
+    private boolean isEquals(TreeNode nodeA, TreeNode nodeB) {
+        if (nodeB == null) {
+            return true;
+        }
+        if (nodeA == null || nodeA.val != nodeB.val) {
+            return false;
+        }
+        return isEquals(nodeA.left, nodeB.left) && isEquals(nodeA.right, nodeB.right);
+    }
+}
+```
+