We only have to shrink the range to find the pair:

class Solution {

public:

```
vector<int> twoSum(vector<int>& numbers, int target) {
int lo=0, hi=numbers.size()-1;
while (numbers[lo]+numbers[hi]!=target){
if (numbers[lo]+numbers[hi]<target){
lo++;
} else {
hi--;
}
}
return vector<int>({lo+1,hi+1});
}
```

};