653. Two Sum IV - Input is a BST

Problem Statement:

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

Example 2:

Input: root = [5,3,6,2,4,null,7], k = 28
Output: false

Constraints:

The number of nodes in the tree is in the range [1, 104].
-104 <= Node.val <= 104
root is guaranteed to be a valid binary search tree.
-105 <= k <= 105

Solution:

java

public class TwoSumIV {
    public boolean findTarget(TreeNode root, int sum) {
        HashSet<Integer> set = new HashSet<>();
        return findTarget(root, sum, set);
    }

    private boolean findTarget(TreeNode root, int sum, HashSet<Integer> set) {
        if (root == null)
            return false;
        if (findTarget(root.left, sum, set) == true)
            return true;
        if (set.contains(sum - root.val))
            return true;
        else
            set.add(root.val);
        return findTarget(root.right, sum, set);
    }
}

653. Two Sum IV - Input is a BST #

Problem Statement: #

Example 1: #

Example 2: #

Constraints: #

Solution: #

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653. Two Sum IV - Input is a BST

Problem Statement:

Example 1:

Example 2:

Constraints:

Solution:

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