思路：双指针。

 1 class Solution(object):
 2     def twoSum(self, numbers, target):
 3         """
 4         :type numbers: List[int]
 5         :type target: int
 6         :rtype: List[int]
 7         """
 8         index1, index2 = 0, len(numbers) - 1
 9         while index1 < index2:
10             if numbers[index1] + numbers[index2] == target:
11                 return [index1 + 1, index2 + 1]
12             elif numbers[index1] + numbers[index2] > target:
13                 index2 -= 1
14             else:
15                 index1 += 1
16 
17 
18 if __name__ == '__main__':
19     solution = Solution()
20     print(solution.twoSum(numbers=[2, 7, 11, 15], target=9))