Construct Binary Tree from Inorder and Postorder Traversal

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode() {}
 *     TreeNode(int val) { this.val = val; }
 *     TreeNode(int val, TreeNode left, TreeNode right) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
class Index{
    int index;
}
class Solution {
    public TreeNode buildTree(int[] inorder, int[] postorder) {
        Index len = new Index();
        len.index = inorder.length - 1; 
        return build(inorder, postorder, 0, inorder.length - 1, len); 
    }
    public TreeNode build(int in[], int post[], int inStrt, int inEnd, Index pIndex){ 

        if (inStrt > inEnd) 
            return null; 
  

        TreeNode node = new TreeNode(post[pIndex.index], null, null); 
        pIndex.index--; 
  

        if (inStrt == inEnd) 
            return node; 
  

        int iIndex = search(in, inStrt, inEnd, node.val); 

        node.right = build(in, post, iIndex + 1, inEnd, pIndex); 
        node.left = build(in, post, inStrt, iIndex - 1, pIndex); 
  
        return node; 
    } 
  
    public int search(int arr[], int strt, int end, int value){ 
        int i;
        for(i = strt; i <= end; i++) { 
            if (arr[i] == value) 
                break; 
        } 
        return i; 
    } 
}