Very similar to my recursive solution of Q105.

```
public TreeNode buildTree(int[] inorder, int[] postorder) {
int n = inorder.length;
// Base case.
if(n == 0)
return null;
// General case.
int rootVal = postorder[n-1];
int rootIndex = 0;
for(int i = 0; i < n; i++) {
if(inorder[i] == rootVal) {
rootIndex = i;
break;
}
}
int leftLength = rootIndex;
int rightLength = n - 1 - leftLength;
TreeNode root = new TreeNode(rootVal);
root.left = buildTree(Arrays.copyOfRange(inorder, 0, leftLength), Arrays.copyOfRange(postorder, 0, leftLength));
root.right = buildTree(Arrays.copyOfRange(inorder, rootIndex + 1, rootIndex + 1 + rightLength), Arrays.copyOfRange(postorder, leftLength, leftLength + rightLength));
return root;
}
```