653-Two-Sum-IV-Input-is-a-BST.js

// 653. Two Sum IV - Input is a BST [Easy]
// https://leetcode.com/problems/two-sum-iv-input-is-a-bst/

/**
 * 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}
 */
const findTarget = (root, k) => {
    const nums = [];

    const traverse = (root) => {
        if (!root) return;

        nums.push(root.val);
        traverse(root.left);
        traverse(root.right);
    };

    traverse(root);
    return twoSum(nums, k);
};

/**
 * @param {number[]} nums
 * @param {number} target
 * @return {number[]}
 */
function twoSum(nums, target) {
    const arr = nums.map((el, idx) => [el, idx]).sort((a, b) => a[0] - b[0]);

    let left = 0;
    let right = nums.length - 1;

    while (left < right) {
        const sum = arr[left][0] + arr[right][0];

        if (sum === target) {
            return true;
        } else if (sum < target) {
            left++;
        } else {
            right--;
        }
    }

    return false;
}