Construct Binary Tree from Inorder and Postorder Traversal Traversal leetcode java

    public TreeNode buildTree(int[] inorder, int[] postorder) {
        return buildTree(inorder, 0, inorder.length-1, postorder, 0, postorder.length-1);
    }
    
        public TreeNode buildTree(int[] in, int inStart, int inEnd, int[] post, int postStart, int postEnd){
         if(inStart > inEnd || postStart > postEnd){
             return null;
        }
        int rootVal = post[postEnd];
        int rootIndex = 0;
        for(int i = inStart; i <= inEnd; i++){
             if(in[i] == rootVal){
                 rootIndex = i;
                 break;
             }
         }
       
         int len = rootIndex - inStart;
         TreeNode root = new TreeNode(rootVal);
         root.left = buildTree(in, inStart, rootIndex-1, post, postStart, postStart+len-1);
         root.right = buildTree(in, rootIndex+1, inEnd, post, postStart+len, postEnd-1);
       
        return root;
     }