Problem with inserting nodes on Binary trees

[Blondeamon]

Ok i'll try to be brief. As part of one of my essays i thought of
creating source code for implementation of a binary tree and its basic
functions.

My code is both from books,lecture notes and googling but for some
reason on the printing of the nodes using inOrder traversal only 2 or 3
nodes are being printed.

I will put my code here although i am sure that only few might actually
comprehend what it is about because this subject needs good knowledge of
all the tricks about inserting/deleting nodes from theory of Binary Trees.


Exercise: Create code for a binary tree.The program reads the size of
the tree N and then inserts N nodes with values between 1 and 30.000
into the tree.
You cant enter a node if it is not already on the tree,so you must
search if it exists before entering it.

Finally ,after having inserted all N nodes print them using InOrder
traversal.


Tips: My code works for the first 2 nodes...but doesnt
print anything else.And i will bust my head open if i wont figure out why.

I appreciate any help guys , this is a tough question and this is my
first time on this forum.
(seems very warm so far btw)

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;

//the struct which represents the node
struct tnode {
        struct tnode *left, *right;
        int key;
};


void InOrder( tnode *x )
{
        if (x == 0) return;
        InOrder(x->left);
        cout << x->key << " ";
        InOrder(x->right);
}


int main ()
{
        srand((long)2004126);
        tnode *root = 0;
        int size, key2;
        int flag;

        cout << "\nPlease enter the size of the tree.  N: ";
        cin >> size;

        for (int i = 0; i < size; i++) {
                key2 = 1 + rand() % 30000;  //creating random node key 
between 1-30.000
                tnode *p = root;
                tnode *q = 0 ;
                flag = 0;

           //searching existing tree for node with that value

                while((p != 0)&&(flag==0)) {
                        q = p;
                        if (p->key == key2) {
                                flag = 1; //node with that key already 
exists -cant enter
                        } else if (p->key < key2) {
                                p = p->left; //case 1: key smaller than root
                        } else {
                                p = p->right; //case 2: key bigger than root
                        }
                }


                  //creating new node with key2 as content
                if (flag == 0) { //flag is 0 when that value didnt 
already exist on the tree
                        tnode *z = new tnode;
                        z->key = key2;
                        z->left = 0;
                        z->right = 0;    //creation of nw node that will 
take key2 as its value
                               //and will have 2 NULL kids (left and right)

                        if (q == 0) {
                                root = z;
                        //case of empty tree
                        //case handling about where the new node will be put
                        } else if (key2 > q->key) {
                                q->right = z;
                        } else {
                                q->left = z;
                        }
                }
        }

        //cout << "\nroot is : "<< root->key;          //not needed 
,just for checking
 
    //the value of root
        InOrder(root);
        cout << endl;
        cin >> size;
        return 0;
}

 

[Nikos Chantziaras]

[...]
Tips:

This isn't a web forum, so I don't think BBcode is supposed to work here.

#include <iostream>
#include <cstdlib>
#include <ctime>

using namespace std;[/QUOTE]

It looks like C++ to me so I guess it's off-topic here.