# Interview Questions

Ritambhara Technologies - Coding Interview Preparations > Interview Questions > Algorithms > Difference between nodes of alternate vertical levels in a tree

# Difference between nodes of alternate vertical levels in a tree

- May 19, 2018
- Posted by: Kamal Rawat
- Category: Algorithms

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*The question below is given in the format in which questions are asked on coding interview Platforms like HackerRank, CodeChef, CodeJam, etc.*

**Solution:**

You can see the question live on hackerrank.com at the link below:

https://www.hackerrank.com/contests/rtech-april-18-01/challenges/vertical-level-sum-differences

Some of the solutions are:

Java

import java.io.*; import java.util.*; public class Solution { Node root; static int odd=0,even=0; public static class Node{ int data; Node left; Node right; Node(int data){ this.data=data; left=null; right=null; } } public static Node insert(int a[],Node root,int i){ if (i < a.length) { if(a[i]==-1){ Node temp = null; } else{ Node temp = new Node(a[i]); root = temp; root.left = insert(a, root.left,2 * i + 1); root.right = insert(a, root.right, 2 * i + 2); } } return root; } public static void print(Node root,int i){ if(root!=null){ print(root.left,i-1); if(i%2==0) even+=root.data; else odd+=root.data; //System.out.println(root.data); print(root.right,i+1); } } public static void main(String[] args) { /* Enter your code here. Read input from STDIN. Print output to STDOUT. Your class should be named Solution. */ Scanner sc=new Scanner(System.in); int n=sc.nextInt(); int a[]=new int[n]; for(int i=0;i<n;i++) a[i]=sc.nextInt(); Solution sol=new Solution(); sol.root=insert(a,sol.root,0); print(sol.root,0); System.out.println((even)-(odd)); } }

C++ Solution:

int a[100005]; int b[100005]; int main() { int n; cin >> n; for(int i = 1 ; i<=n ; i++) { cin >> a[i]; } b[1] = 0; for(int i = 1 ; i<=n ; i++) { b[2*i] = b[i]-1; b[2*i+1] = b[i]+1; } int even = 0 , odd = 0; for(int i = 1 ; i<=n ; i++) { if(abs(b[i])%2==0) { if(a[i]!=-1) { even+=a[i]; } } else { if(a[i]!=-1) { odd+=a[i]; } } } cout << even - odd; return 0; }