LeetCode-in-All
226. Invert Binary Tree
Easy
Given the root of a binary tree, invert the tree, and return its root.
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
Solution
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* struct TreeNode *left;
* struct TreeNode *right;
* };
*/
#include <stdio.h>
#include <stdlib.h>
// Function to invert a binary tree
struct TreeNode* invertTree(struct TreeNode* root) {
if (root == NULL) {
return NULL;
}
// Swap the left and right children
struct TreeNode* temp = root->left;
root->left = invertTree(root->right);
root->right = invertTree(temp);
return root;
}
// Helper function to create a new tree node
struct TreeNode* createNode(int val) {
struct TreeNode* newNode = (struct TreeNode*)malloc(sizeof(struct TreeNode));
newNode->val = val;
newNode->left = NULL;
newNode->right = NULL;
return newNode;
}
// Helper function to print the tree in order (for testing purposes)
void printInOrder(struct TreeNode* root) {
if (root == NULL) return;
printInOrder(root->left);
printf("%d ", root->val);
printInOrder(root->right);
}
// Helper function to free the tree memory
void freeTree(struct TreeNode* root) {
if (root == NULL) return;
freeTree(root->left);
freeTree(root->right);
free(root);
}