LeetCode 167. Two Sum II – Input array is sorted (javascript)

Given an array of integers numbers that is already sorted in ascending order, find two numbers such that they add up to a specific target number.

Return the indices of the two numbers (1-indexed) as an integer array answer of size 2, where 1 <= answer[0] < answer[1] <= numbers.length.

You may assume that each input would have exactly one solution and you may not use the same element twice.

Example 1:

Input: numbers = [2,7,11,15], target = 9
Output: [1,2]
Explanation: The sum of 2 and 7 is 9. Therefore index1 = 1, index2 = 2.

Example 2:

Input: numbers = [2,3,4], target = 6
Output: [1,3]

Example 3:

Input: numbers = [-1,0], target = -1
Output: [1,2]

Constraints:

2 <= numbers.length <= 3 * 10⁴
-1000 <= numbers[i] <= 1000
numbers is sorted in increasing order.
-1000 <= target <= 1000
Only one valid answer exists.

Solution 1: (Two pointer)

/**
 * @param {number[]} numbers
 * @param {number} target
 * @return {number[]}
 */
var twoSum = function(numbers, target) {
    let l = 0;
    let r = numbers.length - 1;
    while (l < r) {
        let sum = numbers[l] + numbers[r];
        if (sum === target) break;
        else if (sum > target) r--;
        else l++;
    }
    // this question use 1-indexed
    return [l + 1, r + 1];
};

Solution 2: (Hash table)

var twoSum = function(numbers, target) {
    let map = new Map;
    for (var i = 0; i < numbers.length; i++) {
        var diff = target - numbers[i];
        if(map.has(diff)) {
            return [map.get(diff), i + 1];
        }
        map.set(numbers[i], i + 1);
    }
};