C ++使用数组插入二进制搜索树

Question

So, within this particular program , I have nodes stored inside an vector of nodes. These nodes contain a user input int ID, int age, and string Name.

This vector is meant to act as a binary search tree that is organized by ID number, and is not worried about being balanced.

Currently I am attempting to write an insert function in which, after the creation of a new node of user input values, it compares it against the root, which is stored at index 1 of the vector.

If it is smaller than the ID at the root, then it is placed into position (root*2). If it is larger than the root, then it is placed into position (root*2 + 1)

However, I am having an extreme amount of difficulty placing into the vector if these two spots are already being taken up by another node.

Is there any way that I could create a loop that would check against the value in the filled spot, and continue looping until it finds an empty spot?

A current example that I'm working with

ID 50, ID 100, ID 75

ID 50 is in position 1.

ID 100 is inserted in position 3, since it is empty (2*1)

ID 75 is attempted to be inserted, but position 3 is filled, so then I need to check it against ID in position 3 using the same algorithm. In this case, since 75 is lower than 100, it would be placed in position 4.

I'm completely stumped as to how to to implement such an algorithm into a loop

Any help would be much appreciated.

Here is my code.

void BST::insert() {

int ID;
int AGE;
string NAME;
bool done = false;

int root = 1;

cout << "Please enter the ID number, age and name" << endl;
do
{
    cin >> ID >> AGE >> NAME;
} while (ID <= 0);



Node *tree = new Node(ID, AGE, NAME);


if (!binaryTree.empty())
{

    do
    {
        Node &n = binaryTree.at(root);
        if (n.ID == 0)
        {
            n.ID = ID;
            n.age = AGE;
            n.name = NAME;
            done = true;
            break;
        }
        else if (ID < n.ID)
        {
            root = 2 * root;
        }
        else
        {
            root = 2 * root + 1;
        }
    } while (done = true);
}

if (binaryTree.empty())
{
    binaryTree.push_back(*tree);
}


start();

}

I am still very new to this language, so any help would be much appreciated!

EDIT:

I fixed some discrepancies and added the code that was suggested, however, now an out_of_bounds exception is being thrown.

Thanks!

Answer 1

My question is essentially, how would I turn such an alogrithm into a while loop/do while loop, etc

Here's an answer that uses pseudocode. You should re-write the loop on your own with a different constuct such as a while , do while or for loop.

But first, some problems with your code.

1. You are comparing Node.ID (an int) to NULL to check if a location in the vector is "empty". NULL has the same semantics as 0 so I am going to assume that no IDs will be 0 . Your code doesn't actually check this, so you may want to handle that case and/or address these design issues.

2. I have no idea why you are dynamically allocating memory with new if you are using a vector to store your nodes. This is likely going to lead to a memory leak.

3. I am assuming you are handling creating a vector of the appropriate size in code you have not posted. If you don't do this, then your code will crash when at throws an exception when root is outside the bounds of the vector.

If it is smaller than the ID at the root, then it is placed into position (root*2). If it is larger than the root, then it is placed into position (root*2 + 1)

4. What if the ID is equal to the ID at the root?

And finally, the code with the goto loop.

int root = 1;

BEGIN LOOP            
    Node &n = binaryTree.at(root);
    if (n.ID == 0)
    {
        n.ID = ID;
        n.age = AGE;
        n.name = NAME;
        BREAK OUT OF LOOP
    }
    else if (ID < n.ID)
    {
        root = 2*root;
    }
    else
    {
        root = 2*root + 1;
    }
REPEAT