Given two non-empty binary trees s and t, check whether tree t has exactly the same structure and node values with a subtree of s. A subtree of s is a tree consists of a node in s and all of this node‘s descendants. The tree s could also be considered as a subtree of itself.
Example 1:
Given tree s:
3
/ 4 5
/ 1 2
Given tree t:
4 / 1 2
Return true, because t has the same structure and node values with a subtree of s.
Example 2:
Given tree s:
3
/ 4 5
/ 1 2
/
0
Given tree t:
4 / 1 2
Return false.
Solution:
Time: O(M *N)
/** * Definition for a binary tree node. * public class TreeNode { * int val; * TreeNode left; * TreeNode right; * TreeNode(int x) { val = x; } * } */ class Solution { public boolean isSubtree(TreeNode s, TreeNode t) { if (s == null) { return false; } if (isSameTree(s, t)) { return true; } return isSubtree(s.left, t) || isSubtree(s.right, t); } private boolean isSameTree(TreeNode s, TreeNode t) { if (s == null && t == null) { return true; } if (s == null || t == null) { return false; } if (s.val != t.val) { return false; } return isSameTree(s.left, t.left) && isSameTree(s.right, t.right); } }
[LC] 572. Subtree of Another Tree
原文：https://www.cnblogs.com/xuanlu/p/12148684.html