Kth Smallest Element in a BST — Inorder Traversal

# Python — iterative inorder
def kthSmallest(root, k):
    stack = []
    curr = root
    while curr or stack:
        while curr: stack.append(curr); curr = curr.left
        curr = stack.pop()
        k -= 1
        if k == 0: return curr.val
        curr = curr.right

// Java
public int kthSmallest(TreeNode root, int k) {
    Deque<TreeNode> stack=new ArrayDeque<>(); TreeNode curr=root;
    while (curr!=null||!stack.isEmpty()) {
        while (curr!=null) { stack.push(curr); curr=curr.left; }
        curr=stack.pop();
        if (--k==0) return curr.val;
        curr=curr.right;
    }
    return -1;
}