Print Postorder traversal from given Inorder and Preorder traversals 

Input:
Inorder traversal in[] = {4, 2, 5, 1, 3, 6}
Preorder traversal pre[] = {1, 2, 4, 5, 3, 6}

Output:
Postorder traversal is {4, 5, 2, 6, 3, 1}


Code:

package trees;

public class N2003_PrintPostOrer {

    class Node{

        int data;
        Node left , right;

        Node(int data){
            this.data = data;
            left = right = null;
        }

    }

    static int findIndex(int element, int[] a, int start, int end){

        int i= -1;

        for(i =start; i<= end; i++){
            if(element == a[i]){
                return i;
            }
        }

        return i;
    }

    static int preIndex = 0;

    static void printPostOrder(int[] in, int[] pre, int start, int end){

        if(start > end){
            return;
        }

        int element = pre[preIndex++];

        if(start != end){

            int index = findIndex(element, in, start, end);
            printPostOrder(in, pre, start, index-1);
            printPostOrder(in, pre, index+1, end);

        }

        System.out.print(element+" ");
        return;

    }
   
    public static void main(String[] args) {
           int in[] = {4, 2, 5, 1, 3, 6};
           int pre[] =  {1, 2, 4, 5, 3, 6};
           printPostOrder(in,pre,0,in.length-1);
    }





}


Output:

4 5 2 6 3 1

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