Mirror image of a binary tree

Question

Suppose there is a tree:

             1
            / \\
           2   3
              / \\
             4   5

Then the mirror image will

Answer 1

TreeNode * mirror(TreeNode *node){
  if(node==NULL){
    return NULL;
  }else{
    TreeNode *temp=node->left;
    node->left=mirror(node->right);
    node->right=mirror(temp);
    return node;
  }
}