private static LeetCode106TreeNode Helper(int left, int right)
{
if (left > right)
{
return(null);
}
var root_val = postOrder[post_idx];
var root = new LeetCode106TreeNode(root_val);
var index = idx_map[root_val];
post_idx--;
root.right = Helper(index + 1, right);
root.left = Helper(left, index - 1);
return(root);
}
public LeetCode106TreeNode(int val = 0, LeetCode106TreeNode left = null, LeetCode106TreeNode right = null)
{
this.val = val;
this.left = left;
this.right = right;
}
