167. Two Sum II - Input array is sorted

time: O(n)

space: O(1)

class Solution {
    public int[] twoSum(int[] numbers, int target) {
        int l = 0;
        int r = numbers.length - 1;
        while (l <= r) {
            int sum = numbers[l] + numbers[r];
            if (sum == target) {
                return new int[]{l+1, r+1};
            } else if (sum > target) {
                r--;
            } else {
                l++;
            }
        }
        return new int[]{};
    }
}

js

var twoSum = function(numbers, target) {
        // two pointer
    let left = 0;
    let right = numbers.length - 1;

    while (left < right) {
        const sum = numbers[left] + numbers[right];
        if (sum == target) {
            return [left+1, right+1];
        }
        if (sum > target) {
            right--;
        } else {
            left++;
        }
    }
    return [];
    
};

py

class Solution(object):
    def twoSum(self, numbers, target):
        """
        :type numbers: List[int]
        :type target: int
        :rtype: List[int]
        """
        left, right = 0, len(numbers)-1
        while left < right:
            sum = numbers[left] + numbers[right]
            
            if sum == target:
                return [left+1, right+1]
            elif sum < target:
                left += 1
            else:
                right -= 1