Compititive_programming_code/Leetcode/New_Question.java at master · Rohit0301/Compititive_programming_code · GitHub

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Given the root of a Binary Search Tree and a target number k, return true if there exist two elements in the BST such that their sum is equal to the given target.


Example 1:


Input: root = [5,3,6,2,4,null,7], k = 9
Output: true


Solution:
if(root==null){

        return false;

    }

    Queue<TreeNode>q = new LinkedList<>();

    HashSet<Integer>ss = new HashSet<>();

    q.offer(root);

    while(!q.isEmpty()){

        int sz = q.size();

        while(sz-->0){

            TreeNode n = q.poll();

            int nn = n.val;

            if(ss.contains(k-nn)){

                return true;
            }

            ss.add(nn);

            if(n.left!=null){

                q.offer(n.left);

            }

            if(n.right!=null){

                q.offer(n.right);
            }


        }


    }

    return false;


}
}