void last_thread(Node *root){
if (root != NULL){
last_thread(root->left->child);
last_thread(root->right->child);
if (root->left->child == NULL){
root->left->child = last;
root->left->tag = LINK;
}
if (last != NULL && last->right->child == NULL){
last->right->child = root;
last->right->tag = LINK;
}
last = root;
}
}
//三.后序线索二叉树
//三.1 后序线索化
//按照"左右根"的顺序进行
void last_thread(Bin_tree tree)
{
if(tree != NULL)
{
last_thread(tree->left_child);
last_thread(tree->right_child);
if(tree->left_child == NULL)
{
tree->left_child = pre;
tree->left_flag = THREAD;
}
if(pre->right_child == NULL)
{
pre->right_child = tree;
pre->right_flag = THREAD;
}
pre = tree;
}
}
int main(){
ThreadTree root;
const char *str = "ABDHM###I##EG###CFK###GL###";
//const char *str = "ABC###DE##F##";
root = create_thread_tree(&str);
last_trav(root);
last_thread(root);
printf("\n");
last_thread_trav(root);
return 0;
}
//三.2 创建后序线索二叉树
//创建新节点root指向原来的tree
Bin_tree create_last_thread(Bin_tree tree)
{
Bin_tree root = NULL;
root = create_node(); //新节点root
root->right_flag = LINK;
root->right_child = root;
if(tree == NULL) //无二叉树时
{
root->left_child = root;
}
else
{
pre = root;
root->left_child = tree; //root指向tree
root->left_flag = LINK;
last_thread(tree); //后序线索化tree
root->right_child = pre;
}
return root;
}
