text: //  Two Sum II - Input array is sorted
  
  class Solution {
  public:
      vector<int> twoSum(vector<int>& numbers, int target) {
          vector<int> res;
          size_t l = 0, r = numbers.size() - 1;
          while (l < r) {
              long sum = numbers[l] + numbers[r];
              if (sum > target)   -- r;
              else if (sum < target)  ++ l;
              else { res.push_back(l+1); res.push_back(r+1); return res; }
          }
          return res;
      }
  };