# Leetcode 167 —— 双指针问题

167. Two Sum II – Input array is sorted

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:

• 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.``````
``````# -*- coding: utf-8 -*-
"""
Created on Wed Mar  6 09:46:09 2019

@author: zhuli02
"""

class Solution(object):
def twoSum(self, numbers, target):
"""
:type numbers: List[int]
:type target: int
:rtype: List[int]
"""
left = 1
right = len(numbers)
while left<right:
a = numbers[left-1]
b = numbers[right-1]
s = a + b
if s == target:
new_list = [left, right]
return new_list
elif s < target:
left += 1
continue
elif s > target:
right -= 1
continue``````