Subtree of Another Tree
LeetCode https://leetcode.cn/problems/subtree-of-another-tree/
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/**
* 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 s, TreeNode t) {
return dfs(s, t);
}
public boolean dfs(TreeNode s, TreeNode t) {
if (s == null) {
return false;
}
return check(s, t) || dfs(s.left, t) || dfs(s.right, t);
}
public boolean check(TreeNode s, TreeNode t) {
if (s == null && t == null) {
return true;
}
if (s == null || t == null || s.val != t.val) {
return false;
}
return check(s.left, t.left) && check(s.right, t.right);
}
}
Complexity
- Time = O(n)
- Space = O(1)
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