Given a Binary Tree, print Left view of it. Left view of a Binary Tree is set of nodes visible when tree is visited from Left side. The task is to complete the function leftView(), which accepts root of the tree as argument. 🔗Goto
Full Code
import java.util.LinkedList;
import java.util.Queue;
import java.io.*;
import java.util.*;
class Node{
int data;
Node left;
Node right;
Node(int data){
this.data = data;
left=null;
right=null;
}
}
class LeftViewBtree {
static Node buildTree(String str){
if(str.length()==0 || str.charAt(0)=='N'){
return null;
}
String ip[] = str.split(" ");
// Create the root of the tree
Node root = new Node(Integer.parseInt(ip[0]));
// Push the root to the queue
Queue<Node> queue = new LinkedList<>();
queue.add(root);
// Starting from the second element
int i = 1;
while(queue.size()>0 && i < ip.length) {
// Get and remove the front of the queue
Node currNode = queue.peek();
queue.remove();
// Get the current node's value from the string
String currVal = ip[i];
// If the left child is not null
if(!currVal.equals("N")) {
// Create the left child for the current node
currNode.left = new Node(Integer.parseInt(currVal));
// Push it to the queue
queue.add(currNode.left);
}
// For the right child
i++;
if(i >= ip.length)
break;
currVal = ip[i];
// If the right child is not null
if(!currVal.equals("N")) {
// Create the right child for the current node
currNode.right = new Node(Integer.parseInt(currVal));
// Push it to the queue
queue.add(currNode.right);
}
i++;
}
return root;
}
static void printInorder(Node root)
{
if(root == null)
return;
printInorder(root.left);
System.out.print(root.data+" ");
printInorder(root.right);
}
public static void main (String[] args) throws IOException{
BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
int t=Integer.parseInt(br.readLine());
while(t > 0){
String s = br.readLine();
Node root = buildTree(s);
Tree g = new Tree();
ArrayList<Integer> result = g.leftView(root);
for(int value : result){
System.out.print(value + " ");
}
System.out.println();
t--;
}
}
}class Tree
{
//Function to return list containing elements of left view of binary tree.
ArrayList<Integer> leftView(Node root)
{
ArrayList<Integer> list = new ArrayList<Integer>();
addLeft(list, root, 0);
return list;
}
void addLeft(ArrayList<Integer> list, Node root, int level){
if(root==null){
return;
}
if(list.size()==level)
list.add(root.data);
addLeft(list,root.left, level+1);
addLeft(list,root.right, level+1);
}
}