/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
public:
    bool isEqual(TreeNode* A, TreeNode* B) {
        if (!B) return true;
        if (!A) return false;
        if (A->val != B->val) return false;
        return isEqual(A->left, B->left) && isEqual(A->right, B->right);
    }
    TreeNode* Found(TreeNode* A, int target) {
        if (!A) return nullptr;
        if (A->val == target) return A;
        TreeNode* ret = Found(A->left, target);
        if (!ret) ret = Found(A->right, target);
        return ret;
    }
    bool isSubStructure(TreeNode* A, TreeNode* B) {
        if (!B) return false;
        if (!A) return false;
        TreeNode* t = Found(A, B->val);
        if (!t) return false;
        if (isEqual(t, B)) return true;
        return isSubStructure(A->left, B) || isSubStructure(A->right, B);
    }
};