class Solution {
    int k, res;

    public int kthLargest(TreeNode root, int k) {
        this.k = k;
        dfs(root);
        return res;
    }

    void dfs(TreeNode root){
        if(root == null) return;
        dfs(root.right);

        k--;
        if(k == 0) res = root.val;

        dfs(root.left);
    }
}