Update KDistanceFromRoot.java

Tree/KDistanceFromRoot.java

@@ -1 +1,135 @@
 
+
+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 KDistanceFromRoot {
+
+    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;
+    }
+
+	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 X[] = br.readLine().trim().split(" ");
+	            int k = Integer.parseInt(X[0]);
+	            String s = br.readLine();
+    	    	Node root = buildTree(s);
+        	    Tree g = new Tree();
+			    ArrayList<Integer> nodes = g.Kdistance(root,k);
+			    for(int i = 0;i<nodes.size();i++){
+			        System.out.print(nodes.get(i)+ " ");
+			    }
+			    System.out.println();
+                t--;
+
+        }
+    }
+
+}
+
+
+
+
+class Tree{
+    class pair{
+        Node node;
+        int level;
+        pair(Node node, int level){
+            this.node = node;
+            this.level = level;
+        }
+    }
+
+
+     ArrayList<Integer> Kdistance(Node root, int k){
+          Queue<pair> PQ = new LinkedList<>();
+          PQ.add(new pair(root, 0));
+
+          ArrayList<Integer> adj = new ArrayList<>();
+
+          while(!PQ.isEmpty()){
+              pair curr = PQ.poll();
+              if(curr.level == k) {
+                  adj.add(curr.node.data);
+              }
+
+              if(curr.level > k) break;
+
+              if(curr.node.left != null) PQ.add(new pair(curr.node.left, curr.level+1));
+              if(curr.node.right != null) PQ.add(new pair(curr.node.right, curr.level+1));
+          }
+
+          return adj;
+     }
+}