LeetCode #167 - Two Sum II - Input array is sorted

题目描述：

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

class Solution {
public:
    vector<int> twoSum(vector<int>& numbers, int target) {
        int i=0;
        int j=numbers.size()-1;
        while(i<j)
        {
            if(numbers[i]+numbers[j]==target)
            {
                vector<int> result;
                result.push_back(i+1);
                result.push_back(j+1);
                return result;
            }
            else if(numbers[i]+numbers[j]<target) i++;
            else if(numbers[i]+numbers[j]>target) j--;
        }
    }
};