Description

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

The function twoSum should return indices of the two numbers such that they add up to the target, where index1 must be less than index2.

Note:

• Your returned answers (both index1 and index2) are not zero-based.
• You may assume that each input would have exactly one solution and you may not use the same element twice.

Example:

Input: numbers = [,,,], target =

Output: [,]

Explanation: The sum of  and  is . Therefore index1 = , index2 = .

题目描述，给定一个已排序的数组，和一个目标值，计算数组中的两个值的和等于目标值时的位置，这里位置不从0开始。

思路： 数组是以排序的，则使用两个指针，分别指向数组的头尾，当两数相加小于目标值是则头指针递增一位，当相加大于目标值值，尾指针递减。

下面是代码，感觉还有优化的地方。先贴出来。

public int[] TwoSum(int[] numbers, int target)

        {

            int[] result = new int[];

            int lo=, hi=numbers.Length-;

            while(lo < hi)

            {

                if (numbers[lo] + numbers[hi] < target) lo++;

                else if (numbers[lo] + numbers[hi] > target) hi--;

                else

                    break;

            }

            result[] = lo + ;

            result[] = hi + ;

            return result;

        }