#include <stdio.h>
#include <stdlib.h>

 // Definition for a binary tree node.
struct TreeNode {
    int val;
    struct TreeNode *left;
    struct TreeNode *right;
};

void printTree(struct TreeNode* tree) {
    if (tree != NULL) {
        printf(" %d ", tree->val);
        printTree(tree->left);
        printTree(tree->right);
    }
}


struct TreeNode* invertTree(struct TreeNode* root){
    if (root != NULL) {
        struct TreeNode* temp = root->right;
        root->right = root->left;
        root->left = temp;
        invertTree(root->left);
        invertTree(root->right);
    }
    return root;
}

int main() {
    struct TreeNode l = { 2, NULL, NULL };
    struct TreeNode r = { 3, NULL, NULL };
    struct TreeNode tree = { 1, &l, &r};
    struct TreeNode* inverted = invertTree(&tree);
    printf("Expected: 1  3  2 \n");
    printf("Got:");
    printTree(inverted);
    printf("\n");
    return 0;
}