binary tree c++ insert and update? - c++

Question

I want to make a binary tree in c++ that perform insert operation the inserted values are 4 on a node that is
name, type , order, and color
The use will enter these 4 as INSERT corn oil 3 yellow. It create a new node with name as corn and 3 child node as type ,order and color.
If again user enter same thing but change any other except name that exists like
INSERT corn oil 4 red as corn name exist this will update node
preorder and postorder traversal with remove and find any node
Here is how i am going ?
struct TreeNode {
string itemname; // The data in this node.
TreeNode *left; // Pointer to the left subtree.
TreeNode *right; // Pointer to the right subtree.
};
1- Name node will have 2 values left right where 4th will be place
2- The hierarchy of tree is like root have only names that have 2 left right node so root have many nodes with names that have only 2 further node but no more node will be added to child node of names is it really a tree

Answer 1

Since you are using binary tree, I am not sure you can use string as a key for TreeNode (well I have always used intigers). So what I suggest is that you have structure like this:
// I am not sure about types, but I assumed them by name
struct Element {
char* name;
int type;
int order;
char* color;
};
struct TreeNode {
int key;
Element *element;
TreeNode *left, *right;
};
Then you would somehow calculate hash of Element::name to get a numeric value, which a is key. Now you would just traverse tree from root to the left or right depending on key. You would check on each node if key you are inserting is same as one in current node and if answer is yes, then you would swap values in that node, otherwise continue traversing the tree to the left or right. If you get to the bottom it means you haven't find a node with that key, so you create a new one and attach it as a leaf.
You can look this link to generate hash. However, keep in mind that for some string you can get same hash value, so you may need to keep more than one element at the current tree node.
UPDATE
Here is the code, however you can optimize it more by using pointers. But as mentioned in comments, if you are not strictly bound to use binary tree, you should use HashTable or std::map.
std::map<std::string, struct Element*> elements
and for retrieving element:
Element *e = elements["corn"]
Binary Tree implementation:
#include <iostream>
#include <vector>
#define A 54059 /* a prime */
#define B 76963 /* another prime */
#define C 86969 /* yet another prime */
#define FIRSTH 37 /* also prime */
struct Element {
std::string name;
std::string type;
int order;
std::string color;
};
struct TreeNode {
int key;
std::vector<Element> values;
struct TreeNode *left;
struct TreeNode *right;
};
/**
* see: https://stackoverflow.com/questions/8317508/hash-function-for-a-string
*/
int calculateHash(const char *s)
{
int h = FIRSTH;
while (*s) {
h = (h * A) ^ (s[0] * B);
s++;
}
return h; // or return h % C;
}
void printElement(Element element)
{
std::cout
<< element.name
<< " "
<< element.type
<< " "
<< element.order
<< " "
<< element.color
<< std::endl;
}
void preOrder(TreeNode* node)
{
if( node == NULL )
return;
for(size_t i=0; i<node->values.size(); i++) {
printElement(node->values[i]);
}
preOrder(node->left);
preOrder(node->right);
}
void insert(TreeNode** root, Element element, int key)
{
if( *root == NULL ) {
TreeNode* node = new TreeNode();
node->key = key;
node->values.push_back(element);
*root = node;
return;
};
if( key == (*root)->key ) {
for(size_t i=0; i<(*root)->values.size(); i++) {
if( (*root)->values[i].name == element.name ) {
(*root)->values[i].type = element.type;
(*root)->values[i].order = element.order;
(*root)->values[i].color = element.color;
break;
}
}
}
else if( key < (*root)->key ) {
insert( &((*root)->left), element, key );
}
else {
insert( &((*root)->right), element, key );
}
}
int main()
{
TreeNode *node = NULL;
insert(&node, {"corn1", "oil", 3, "yellow"}, calculateHash("corn1"));
insert(&node, {"corn2", "oil", 3, "yellow"}, calculateHash("corn2"));
insert(&node, {"corn3", "oil", 3, "yellow"}, calculateHash("corn3"));
insert(&node, {"corn2", "aaa", 32, "blue"}, calculateHash("corn2"));
preOrder(node);
return 0;
}