c++ - What is logic to construct a binary tree? -

i have while loop continuously takes integers until -1 entered. elements must inserted binary tree (not bst). if bst, have condition insert new node. how can construct binary tree?

i mean if nodes 1,2,3,4,5,6..., 1 root, 2 , 3 left , right children of node 1, 4 , 5 left , right children of node 2, , 6 left child of node 3, this:

if(root==null)     root= newnode;  else{     if (root->left==null)          root->left= insert(root->left,element);      else          root->right= insert(root->right,element);  } return root; 

how create tree this?

the algorithm outlined whozcraig in comment can realized code:

/* create binary tree nodes presented in bfs order */ #include <cassert> #include <iostream> #include <vector> #include <iomanip>  using std::vector; using std::cout; using std::cin; using std::ostream; using std::setw;  struct node {     int data;     node *left;     node *right;     node(int n) : data(n), left(0), right(0) { } };  void print_bt(const node *root);  int main() {     vector<node> v;     int n;      // read data eof or negative value     while (cin >> n && n >= 0)         v.push_back(node(n));      // create binary tree     (size_t = 0; < v.size()/2; i++)     {         assert(2*i+1 < v.size());         v[i].left = &v[2*i+1];         if (2*i+2 < v.size())             v[i].right = &v[2*i+2];     }      // print binary tree     print_bt(&v[0]);      return 0; }  // print_bt() presents data if mentally rotate // output through 90º clockwise (so root @ top), // left child appears on left , right on right.  reversing // order of left/right leaves confusing. void print_bt(const node *root) {     static int level = 0;     if (root != nullptr)     {         level++;         print_bt(root->right);         cout << setw(4*level) << root->data << '\n';         print_bt(root->left);         level--;     } } 

for example, given numbers 1 6 input, produces:

       3            6    1            5        2            4 

and given numbers 1 15 input, produces:

              15            7               14        3               13            6               12    1               11            5               10        2                9            4                8 

it helps if visualize tree rotated 90º clockwise, 1 @ top.