How can I create the tree?
I'm trying to make a BST and need to print it inorder, postorder, and preorder.
The thing am not sure about is how to create this tree in my main()
function.
struct Tree_Node
{
Tree_Node *right;
Tree_Node *left;
int info;
};
class bTree
{
private:
Tree_Node *root;
public:
bTree();
void bTree::Insert(Tree_Node*& tree, int item);
void bTree::preorderPrint(Tree_Node *root);
};
bTree::bTree()
{
root = NULL;
}
void bTree::Insert(Tree_Node*& tree, int item)
{
if (tree == NULL)
{
tree = new Tree_Node;
tree->right = NULL;
tree->left = NULL;
tree->info = item;
}
else if (item < tree->info)
Insert(tree->left, item);
else
Insert(tree->right, item);
}
void bTree::preorderPrint(Tree_Node *root)
{
if ( root != NULL )
{
cout << root->info << " ";
preorderPrint( root->left );
preorderPrint( root->right );
}
}
void main()
{
// This is where I need help at
// I'm not sure how to insert开发者_如何学JAVA a new node
bTree Test;
Test.Insert(
}
By the looks of things, you can just write
Test.Insert(Test.root, 3); // Insert 3
Test.Insert(Test.root, 4); // Insert 4
and that should work. Of course, you'll have to make root public.
However, this is a bit awkward, since the first parameter will always be bTree.root - and you don't need to make that public. Remember that the user of your data type (you or anyone else) shouldn't have to care about internals such as nodes - they only care about their data. Instead, I'd recommend making a convenience Insert
method which only needs to take an integer (not a tree node) - this is called Overloading.
void bTree::Insert(int item)
{
Insert(root, item);
}
// Keep the other insert method, but make it private.
Then you can just write:
Test.Insert(3);
Test.Insert(4);
void bTree::Insert(int item)
{
Tree_Node * node = new Tree_Node;
node->left = NULL;
node->right = NULL;
node->info = item;
if (root == NULL)
{
root = node;
return;
}
Tree_Node * t = root;
Tree_Node * p = root;
while(1)
{
if (item < t->info)
{
t = t->left;
if(t == NULL)
{
p->left = node;
return;
}
}
else if(item > t->info)
{
t = t->right;
if(t == NULL)
{
p->right = node;
return;
}
}
else //item already exists in the tree
return;
p = t;
}
}
//now you can insert nodes like
Test.Insert(5);
Test.Insert(6);
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