二叉树树的子结构

Posted 2020-08-09 梵高先生

输入两棵二叉树A，B，判断B是不是A的子结构。（ps：我们约定空树不是任意一个树的子结构）

 1 /**
 2 public class TreeNode {
 3     int val = 0;
 4     TreeNode left = null;
 5     TreeNode right = null;
 6 
 7     public TreeNode(int val) {
 8         this.val = val;
 9 
10     }
11 
12 }
13 */
14 public class Solution {
15     public boolean HasSubtree(TreeNode root1,TreeNode root2) {
16 
17          boolean result = false;
18          
19          if(root1 != null && root2 != null){
20              
21              if(root1.val == root2.val){
22                  result = DoesTree1HasTree2(root1,root2);
23              }
24              
25             //递归遍历左子树 
26             if(!result){
27                 result = HasSubtree(root1.left, root2);
28             }
29             
30             //递归遍历右子树
31             if(!result){
32                 result = HasSubtree(root1.right, root2);
33             }
34          }
35         
36         return result;
37     
38     }
39     
40     
41     public boolean DoesTree1HasTree2(TreeNode root1,TreeNode root2){
42         
43         if(root2 == null){
44             return true;
45         }
46         
47         if(root1 == null){
48             return false;
49         }
50         
51         if(root1.val != root2.val){
52             return false;
53         }
54         
55         return DoesTree1HasTree2(root1.left, root2.left) && DoesTree1HasTree2(root1.right, root2.right);
56     }
57 }