226. Invert Binary Tree
1. Description
Invert a binary tree.
2. Solutions
Recursive
n is the number of nodes in root
Time complexity: O(n)
Space complexity: O(n)
class Solution {
public:
TreeNode* invertTree(TreeNode* root) {
if (root != nullptr) {
root->left = invertTree(root->left);
root->right = invertTree(root->right);
swap(root->left, root->right);
return root;
} else {
return nullptr;
}
}
};