572 - Subtree of Another Tree

572 - Subtree of Another Tree

Given the roots of two binary trees root and subRoot, return true if there is a subtree of root with the same structure and node values of subRoot and false otherwise.

A subtree of a binary tree tree is a tree that consists of a node in tree and all of this node's descendants. The tree tree could also be considered as a subtree of itself.

Examples

Input: root = [3,4,5,1,2], subRoot = [4,1,2] Output: true

Input: root = [3,4,5,1,2,null,null,null,null,0], subRoot = [4,1,2] Output: false

Constraints

• The number of nodes in the root tree is in the range [1, 2000].

• The number of nodes in the subRoot tree is in the range [1, 1000].

• -104 <= root.val <= 104

• -104 <= subRoot.val <= 104

Java Solution

/**
 * 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(areSame(root,subRoot)){
            return true;
        }else{
            return isSubtree(root.left,subRoot) || isSubtree(root.right,subRoot);
        }
    }
    
    public boolean areSame(TreeNode curr,TreeNode subRoot){
        if(curr==null && subRoot==null){
            return true;
        }else if(curr==null || subRoot==null){
            return false;
        }else{
            if(curr.val!=subRoot.val){
                return false;
            }
            if(areSame(curr.left,subRoot.left)==false || areSame(curr.right,subRoot.right)==false){
                return false;
            }
            return true;
        } 
    }
}