Create Ceil in BST.java

Java/Java/Ceil in BST.java

@@ -0,0 +1,161 @@
+/*
+Ceil in BST
+Difficulty Level : Medium
+Given a BST and a number X, find Ceil of X.
+Note: Ceil(X) is a number that is either equal to X or is immediately greater than X.
+If Ceil could not be found, return -1.
+Example 1:
+Input:
+      5
+    /   \
+   1     7
+    \
+     2 
+      \
+       3
+X = 3
+Output: 3
+Explanation: We find 3 in BST, so ceil
+of 3 is 3.
+
+Example 2:
+Input:
+     10
+    /  \
+   5    11
+  / \ 
+ 4   7
+      \
+       8
+X = 6
+Output: 7
+Explanation: We find 7 in BST, so ceil
+of 6 is 7.
+*/
+
+
+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 GfG {
+
+    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();
+            int n = Integer.parseInt(br.readLine());
+            Node root = buildTree(s);
+            Tree g = new Tree();
+            System.out.println(g.findCeil(root, n));
+            t--;
+        }
+    }
+}
+
+// } Driver Code Ends
+
+
+// User function Template for Java
+
+class Tree {
+    // Function to return the ceil of given number in BST.
+    int findCeil(Node root, int key) {
+        if (root == null) return -1;
+        // Code here
+        int res = -1;
+        while(root!=null)
+        {
+            if(root.data==key)
+                return key;
+            if(root.data<key)
+                root = root.right;
+            else
+            {
+                res = root.data;
+                root = root.left;
+            }
+        }
+        return res;
+    }
+}