167. Two Sum II - Input array is sorted

Not much to say. An easy two pointers solution with O(N) running time. Of course, it can be solved by binary search but it may cost NlogN running time.

1:  class Solution {  
2:  public:  
3:    vector<int> twoSum(vector<int>& numbers, int target) {  
4:      int l = 0, r = numbers.size()-1;  
5:      while (l < r) {  
6:        int sum = numbers[l] + numbers[r];  
7:        if (sum == target) break;  
8:        else if (sum < target) l++;  
9:        else r--;  
10:      }  
11:      return vector<int>{l+1, r+1};  
12:    }  
13:  };