572. Subtree of Another Tree

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572. Subtree of Another Tree

Description

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.

Example 1:

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

Example 2:

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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].
  • -10^4 <= root.val <= 10^4
  • -10^4 <= subRoot.val <= 10^4

Hints/Notes

Solution

Language: C++

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left),
 * right(right) {}
 * };
 */
class Solution {
public:
    bool isSubtree(TreeNode* root, TreeNode* subRoot) {
        if (!root && !subRoot) {
            return true;
        }
        if (!root || !subRoot) {
            return false;
        }
        bool ans = false;
        if (root->val == subRoot->val) {
            ans = validate(root, subRoot);
        }
        if (ans) {
            return true;
        } else {
            return isSubtree(root->left, subRoot) ||
                   isSubtree(root->right, subRoot);
        }
    }

    bool validate(TreeNode* root, TreeNode* subRoot) {
        if (!root && !subRoot) {
            return true;
        }
        if (!root || !subRoot) {
            return false;
        }
        if (root->val != subRoot->val) {
            return false;
        }
        return validate(root->left, subRoot->left) &&
               validate(root->right, subRoot->right);
    }
};