LeetCode/Solutions/BST/572. Subtree of Another Tree/Solution.java at master · worldlightyjx/LeetCode · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
class Solution {
    public boolean isSubtree(TreeNode root, TreeNode subRoot) {
        if (root == null)
            return false;
        if (isSame(root, subRoot))
            return true;
        return isSubtree(root.left, subRoot) || isSubtree(root.right, subRoot);

    }

    private boolean isSame(TreeNode r1, TreeNode r2) {
        if (r1 == null && r2 == null)
            return true;
        if (r1 == null || r2 == null)
            return false;

        if (r1.val != r2.val)
            return false;

        return isSame(r1.left, r2.left) && isSame(r1.right, r2.right);
    }
}