PreorderToPostorder

PreorderToPostorderBST.java

@@ -0,0 +1,96 @@
+/*package whatever //do not write package name here */
+
+import java.util.*;
+import java.lang.*;
+import java.io.*;
+
+class Node{
+    int data;
+    Node left;
+    Node right;
+
+    public Node(int d)
+    {
+        data=d;
+        left=right=null;
+    }
+
+
+    public Node create(Node root,int x)
+    {
+        Node ptr=root;
+        Node s = new Node(x);
+
+        while(true)
+        {
+            if(ptr.data<x)
+            {
+                if(ptr.right==null)
+                {
+                    ptr.right=s;
+                    break;
+                }
+                else{
+                    ptr=ptr.right;
+                }
+
+            }
+            else
+            {
+                if(ptr.left==null)
+                {
+                    ptr.left=s;
+                    break;
+                }
+                else{
+                    ptr=ptr.left;
+                }
+
+            }
+        }
+
+        return root;
+    }
+
+    public void  traverse(Node s)
+    {
+        if(s!=null)
+        {
+            traverse(s.left);   
+            traverse(s.right);
+            System.out.print(s.data+" ");
+        }
+    }
+
+
+
+}
+
+
+
+class GFG {
+	public static void main (String[] args) {
+	    Scanner sc = new Scanner(System.in);
+		int t = sc.nextInt();
+		while(t-- > 0)
+		{
+		    int a = sc.nextInt();
+		    int arr[] = new int[a];
+
+		    for(int i=0;i<a;i++)
+		    {
+		        arr[i]=sc.nextInt();   
+		    }
+
+		   Node n = new Node(arr[0]); 
+
+		   for(int i=1;i<a;i++)
+		   n = n.create(n,arr[i]); 
+
+		   n.traverse(n); 
+
+
+		   System.out.println(); 
+		}
+	}
+}