Subtree of Another Tree Problem & Solution
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.
See the subtree of another tree problem on LeetCode.
C++ Solution
#pragma GCC optimize("Ofast")
#pragma GCC optimization("max-inline-insns-recursive-auto")
static const int _=[](){ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);return 0;}();
/**
* 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 == nullptr || subRoot == nullptr) {
return false;
}
bool result = false;
if (root->val == subRoot->val) {
result = testSubtree(root, subRoot);
}
return result ||
isSubtree(root->left, subRoot) ||
isSubtree(root->right, subRoot);
}
private:
bool testSubtree(TreeNode* root, TreeNode* subRoot) {
if (root == nullptr && subRoot == nullptr) {
return true;
}
if ((root && !subRoot) || (!root && subRoot)) {
return false;
}
return root->val == subRoot->val &&
testSubtree(root->left, subRoot->left) &&
testSubtree(root->right, subRoot->right);
}
};