Java Simple PriorityQueue Solution

  • 1

    Just insert treenode into queue sorted by the abs(node.val - target) and take the first k ones.

    public List<Integer> closestKValues(TreeNode root, final double t, int k) {
        List<Integer>ret = new ArrayList<Integer>();
        PriorityQueue<TreeNode> queue = new PriorityQueue<TreeNode>(new Comparator<TreeNode>(){
           public int compare(TreeNode n1, TreeNode n2) {
               return Math.abs(n1.val - t) < Math.abs(n2.val - t) ? -1 : 1;
        findClosest(root, queue);
        while(k-- > 0) ret.add(queue.poll().val);
        return ret;
    public void findClosest(TreeNode root, PriorityQueue<TreeNode> queue) {
        if(root == null) return;
        findClosest(root.left, queue);
        findClosest(root.right, queue);

  • 0

    This is NLogN right? Since it takes O(N) to go through the tree and LogN to add to the queue? WOuld this be acceptable solution to give in interview?

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