653. Two Sum IV - Input is a BST

Two Sum IV - Input is a BST

Problem Description

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

Code:

/**
 * Definition for a binary tree node.
 * function TreeNode(val, left, right) {
 *     this.val = (val===undefined ? 0 : val)
 *     this.left = (left===undefined ? null : left)
 *     this.right = (right===undefined ? null : right)
 * }
 */
/**
 * @param {TreeNode} root
 * @param {number} k
 * @return {boolean}
 */


var findTarget = function(root, k) {
    let set = new Set();
    return helper(root, k, set);
};


let helper = function(root, k, set){
    if(root==null){
        return false;
    }
    if(set.has(k-root.val)){
        return true;
    }
    set.add(root.val);
    return (helper(root.left, k, set) || helper(root.right, k, set));
}

Conclusion

That’s all folks! In this post, we solved LeetCode problem #653. Two Sum IV - Input is a BST

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You can find the complete source code on my GitHub repository. If you like what you learn. feel free to fork 🔪 and star ⭐ it.

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Happy coding!