将二叉树的两个孩子交换

struct BTree
{
    int data;
    struct BTree *left;
    struct BTree *right;
};

void *change(BTree *root)
{
    if (root == NULL)
        return;

    BTree *temp = root->left;
    root->left = root->right;
    root->right = temp;

    change(root->left);
    change(root->right);
}
//非递归实现
void *change(BTree * change)
{
    if (change == NULL)
        return;

    Queue qu;
    qu.push(change);
    BTree *ptree;

    while (!qu.empty())
    {
        ptree = qu.front();
        qu.pop();
        BTree *temp = ptree->left;
        ptree->left = ptree->right;
        ptree->right = temp;

        if (ptree->left != NULL)
            qu.push(ptree->left);

        if (ptree->right != NULL)
            qu.push(ptree->right);
    }
}