Print all K-sum levels in a Binary Tree - GeeksforGeeks

26 Jan, 2022
Given a Binary Tree and an integer K where the tree has positive and negative nodes, the task is to print the elements of the level whose sum equals K. If no such result exists, then print “Not Possible“.
Examples: 
Input: 
            -10
           /    \
          2      -3
        /   \       \
       4     15      -6
      /       \      /
     7         -8   9 
K = 13
Output: 4 15 -6
Explanation: 
Level 1 (-10): Sum = -10
Level 2 (2, 3): Sum = 5
Level 3 (4, 15, -6): Sum = 13
Level 4 (7, -8, 9): Sum = 8
Only level 3 (4, 15, -6) has sum = K

Input:
                  1
                /  \ 
              12    13 
             /     /   \ 
            11    6    -11 
                   \    / 
                   2   2  
K = 30
Output:  Not Possible
Explanation: 
There is no such level whose sum = K
Approach: 
Perform level order traversal of the Binary tree and store find the sum of each level.
If the sum is equal to K, print the level. Else move to the next level.
The process is repeated till all the levels has been traversed and checked.
If there is no such level with sum K, print “Not Possible”.
Below is the implementation of the above approach: 
C++
Java
Python3
C#
Javascript
// C++ program to print all// K-sum levels in a Binary Tree#include <bits/stdc++.h>using namespace std; // Vector to store the// elements of a levelvector<int> level; // Binary Tree Nodestruct node {    struct node* left;    int data;    struct node* right;}; // Function to display elementsvoid display(bool flag){     // Check if boolean variable is true    // then print the level    if (flag) {         for (auto x : level)            cout << x << " ";    }     else         cout << "Not Possible\n";} // Function to find sum of// elements by level order traversalvoid SumlevelOrder(node* root, int k){     if (root == NULL)        return;     // Queue data structure for    // level order traversal    queue<node*> q;     // Enqueue Root in Queue    q.push(root);     bool flag = false;     while (q.empty() == false) {         // number of nodes at current level        int nodeCount = q.size();         int Present_level_sum = 0;         // Dequeue all nodes of current level and        // Enqueue all nodes of next level        while (nodeCount > 0) {             node* node = q.front();             // To add node data            Present_level_sum += node->data;             level.push_back(node->data);             q.pop();             if (node->left != NULL)                q.push(node->left);             if (node->right != NULL)                q.push(node->right);             nodeCount--;        }         if (Present_level_sum == k) {             flag = true;            break;        }         level.clear();    }     display(flag);} // Function to create a new tree nodenode* newNode(int data){    node* temp = new node;    temp->data = data;    temp->left = NULL;    temp->right = NULL;    return temp;} // Driver codeint main(){    // Create binary tree    node* root = newNode(1);     root->left = newNode(2);    root->right = newNode(3);     root->left->left = newNode(4);    root->left->right = newNode(5);    root->right->right = newNode(6);     int K = 15;     SumlevelOrder(root, K);     return 0;}
// Java program to print all// K-sum levels in a Binary Treeimport java.util.*; class GFG{  // Vector to store the// elements of a levelstatic Vector<Integer> level = new Vector<Integer>();  // Binary Tree Nodestatic class node {    node left;    int data;    node right;};  // Function to display elementsstatic void display(boolean flag){      // Check if boolean variable is true    // then print the level    if (flag) {          for (Integer x : level)            System.out.print(x+ " ");    }      else          System.out.print("Not Possible\n");}  // Function to find sum of// elements by level order traversalstatic void SumlevelOrder(node root, int k){      if (root == null)        return;      // Queue data structure for    // level order traversal    Queue<node> q = new LinkedList<>();      // Enqueue Root in Queue    q.add(root);      boolean flag = false;      while (q.isEmpty() == false) {          // number of nodes at current level        int nodeCount = q.size();          int Present_level_sum = 0;          // Dequeue all nodes of current level and        // Enqueue all nodes of next level        while (nodeCount > 0) {              node node = q.peek();              // To add node data            Present_level_sum += node.data;              level.add(node.data);              q.remove();              if (node.left != null)                q.add(node.left);              if (node.right != null)                q.add(node.right);              nodeCount--;        }          if (Present_level_sum == k) {              flag = true;            break;        }          level.clear();    }      display(flag);}  // Function to create a new tree nodestatic node newNode(int data){    node temp = new node();    temp.data = data;    temp.left = null;    temp.right = null;    return temp;}  // Driver codepublic static void main(String[] args){    // Create binary tree    node root = newNode(1);      root.left = newNode(2);    root.right = newNode(3);      root.left.left = newNode(4);    root.left.right = newNode(5);    root.right.right = newNode(6);      int K = 15;      SumlevelOrder(root, K);  }} // This code is contributed by 29AjayKumar
# Python3 program to print all# K-sum levels in a Binary Treefrom collections import deque as queue # A BST nodeclass Node:         def __init__(self, x):                 self.data = x        self.left = None        self.right = None # Vector to store the# elements of a levellevel = [] # Function to display elementsdef display(flag):         # Check if boolean variable is    # true then print level    if (flag):        for x in level:            print(x, end = " ")    else:        print("Not Possible\n") # Function to find sum of elements# by level order traversaldef SumlevelOrder(root, k):         if (root == None):        return     # Queue data structure for    # level order traversal    q = queue()     # Enqueue Root in Queue    q.append(root)     flag = False     while (len(q) > 0):         # Number of nodes at current level        nodeCount = len(q)         Present_level_sum = 0         # Dequeue all nodes of current level        # and Enqueue all nodes of next level        while (nodeCount > 0):            node = q.popleft()             # To add node data            Present_level_sum += node.data             level.append(node.data)             # q.pop()             if (node.left != None):                q.append(node.left)             if (node.right != None):                q.append(node.right)             nodeCount -= 1         if (Present_level_sum == k):            flag = True            break         level.clear()     display(flag) # Driver codeif __name__ == '__main__':         # Create binary tree    root = Node(1)     root.left = Node(2)    root.right = Node(3)     root.left.left = Node(4)    root.left.right = Node(5)    root.right.right = Node(6)     K = 15     SumlevelOrder(root, K) # This code is contributed by mohit kumar 29
// C# program to print all// K-sum levels in a Binary Treeusing System;using System.Collections.Generic; class GFG{   // List to store the// elements of a levelstatic List<int> level = new List<int>();   // Binary Tree Nodeclass node {    public node left;    public int data;    public node right;};   // Function to display elementsstatic void display(bool flag){       // Check if bool variable is true    // then print the level    if (flag) {           foreach (int x in level)            Console.Write(x+ " ");    }       else           Console.Write("Not Possible\n");}   // Function to find sum of// elements by level order traversalstatic void SumlevelOrder(node root, int k){       if (root == null)        return;       // Queue data structure for    // level order traversal    Queue<node> q = new Queue<node>();       // Enqueue Root in Queue    q.Enqueue(root);       bool flag = false;       while (q.Count!=0) {           // number of nodes at current level        int nodeCount = q.Count;           int Present_level_sum = 0;           // Dequeue all nodes of current level and        // Enqueue all nodes of next level        while (nodeCount > 0) {               node node = q.Peek();               // To add node data            Present_level_sum += node.data;               level.Add(node.data);               q.Dequeue();               if (node.left != null)                q.Enqueue(node.left);               if (node.right != null)                q.Enqueue(node.right);               nodeCount--;        }           if (Present_level_sum == k) {               flag = true;            break;        }           level.Clear();    }       display(flag);}   // Function to create a new tree nodestatic node newNode(int data){    node temp = new node();    temp.data = data;    temp.left = null;    temp.right = null;    return temp;}   // Driver codepublic static void Main(String[] args){    // Create binary tree    node root = newNode(1);       root.left = newNode(2);    root.right = newNode(3);       root.left.left = newNode(4);    root.left.right = newNode(5);    root.right.right = newNode(6);       int K = 15;       SumlevelOrder(root, K);   }}  // This code is contributed by sapnasingh4991
<script> // Javascript program to print all// K-sum levels in a Binary Tree // Vector to store the// elements of a levellet level = []; // Binary Tree Nodeclass Node{         // Utility function to create a new node    constructor(key)    {        this.data = key;        this.left = this.right = null;    }} // Function to display elementsfunction display(flag){         // Check if boolean variable is true    // then print the level    if (flag)    {        for(let x = 0; x < level.length; x++)            document.write(level[x] + " ");    }    else        document.write("Not Possible<br>");} // Function to find sum of// elements by level order traversalfunction SumlevelOrder(root, k){    if (root == null)        return;       // Queue data structure for    // level order traversal    let q = [];       // Enqueue Root in Queue    q.push(root);       let flag = false;       while (q.length != 0)    {                 // Number of nodes at current level        let nodeCount = q.length;           let Present_level_sum = 0;           // Dequeue all nodes of current level and        // Enqueue all nodes of next level        while (nodeCount > 0)        {            let node = q[0];               // To add node data            Present_level_sum += node.data;               level.push(node.data);            q.shift();               if (node.left != null)                q.push(node.left);               if (node.right != null)                q.push(node.right);               nodeCount--;        }                   if (Present_level_sum == k)        {            flag = true;            break;        }        level = [];    }    display(flag);} // Driver codelet root = new Node(1); root.left = new Node(2);root.right = new Node(3); root.left.left = new Node(4);root.left.right = new Node(5);root.right.right = new Node(6); let K = 15; SumlevelOrder(root, K); // This code is contributed by unknown2108 </script>
4 5 6
 
29AjayKumar
sapnasingh4991
mohit kumar 29
anikakapoor
unknown2108
adnanirshad158
Binary Tree
tree-level-order
Queue
Stack
Tree
Stack
Queue
Tree
Writing code in comment?
Please use ide.geeksforgeeks.org,
generate link and share the link here.
Construct Complete Binary Tree from its Linked List Representation
Iterative Letter Combinations of a Phone Number
FIFO (First-In-First-Out) approach in Programming
Applications of Priority Queue
Reversing a Queue
Stack Data Structure (Introduction and Program)
Stack Class in Java
Stack in Python
Check for Balanced Brackets in an expression (well-formedness) using Stack
Stack | Set 2 (Infix to Postfix)