【数据结构与算法】翻转二叉树

struct TreeNode {
    int val;
    struct TreeNode* left;
    struct TreeNode* right;
    
};
typedef struct TreeNode TNode;
struct TreeNode* invertTree(struct TreeNode* root)
{
    if (root == NULL)//空树的情况
        return NULL;
    if (root->left == NULL && root->right == NULL)//没有子节点的情况
        return root;

    TNode* tmp = root->left;//左右指针交换
    root->left = root->right;
    root->right = tmp;

    invertTree(root->left);//对子树递归调用
    invertTree(root->right);
    return root;
}