problem-solving-with-c-and-cpp/tree_inp_val.cpp at main · mahfuzHasan2003/problem-solving-with-c-and-cpp · GitHub

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#include <bits/stdc++.h>
using namespace std;

class Node
{
public:
   int val;
   Node *left;
   Node *right;
   Node(int val)
   {
      this->val = val;
      this->left = NULL;
      this->right = NULL;
   }
};

Node *input_tree()
{
   int val;
   cin >> val;

   Node *root;
   if (val == -1)
      root = NULL;
   else
      root = new Node(val);
   queue<Node *> q;
   if (root)
      q.push(root);

   while (!q.empty())
   {
      // -------- DIVIDER: STEP 1: --------
      Node *f = q.front();
      q.pop();

      // -------- DIVIDER: STEP 2: --------
      int l, r;
      cin >> l >> r;

      Node *left, *right;
      if (l == -1)
         left = NULL;
      else
         left = new Node(l);
      // ----
      if (r == -1)
         right = NULL;
      else
         right = new Node(r);

      f->left = left;
      f->right = right;

      // -------- DIVIDER: STEP 3: --------
      if (f->left)
         q.push(f->left);
      if (f->right)
         q.push(f->right);
   }

   return root;
}

void print_level_order(Node *root)
{
   if (!root)
      return;
   queue<Node *> q;
   q.push(root);
   while (!q.empty())
   {
      Node *f = q.front();
      q.pop();

      cout << f->val << " ";

      if (f->left)
         q.push(f->left);
      if (f->right)
         q.push(f->right);
   }
}

int main()
{

   Node *root = input_tree();
   print_level_order(root);
   return 0;
}