递归C++ | #树的子结构#

/*
struct TreeNode {
	int val;
	struct TreeNode *left;
	struct TreeNode *right;
	TreeNode(int x) :
			val(x), left(NULL), right(NULL) {
	}
};*/
class Solution {
public:
	bool check_preOrder(TreeNode* root1, TreeNode* root2){
		if (!root2) return true;
		else if (!root1 || root1->val != root2->val) return false;
		else return check_preOrder(root1->left, root2->left) && check_preOrder(root1->right, root2->right);
	}
    bool HasSubtree(TreeNode* pRoot1, TreeNode* pRoot2) {
		if (!pRoot1 || !pRoot2) return false;
		else return check_preOrder(pRoot1, pRoot2) || HasSubtree(pRoot1->left, pRoot2) || HasSubtree(pRoot1->right, pRoot2);
    }
};

前序递归