Invert Binary Tree
Problem Statement - link #
Given the root of a binary tree, invert the tree, and return its root.
Examples #
Example 1:
Input: root = [4,2,7,1,3,6,9]
Output: [4,7,2,9,6,3,1]
Example 2:
Input: root = [2,1,3]
Output: [2,3,1]
Example 3:
Input: root = []
Output: []
Constraints #
- The number of nodes in the tree is in the range
[0, 100]. -100 <= Node.val <= 100
Solutions #
/**
* 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:
void rc(TreeNode* root){
if(root==NULL or (!root->left and !root->right)) return;
TreeNode *post, *pre;
pre = root->left;
post = root->right;
root->left = post;
root->right = pre;
rc(root->left);
rc(root->right);
}
TreeNode* invertTree(TreeNode* root) {
if(!root) return root;
rc(root);
return root;
}
};