1. Two Sum

Given an array of integers, return indices of the two numbers such that they add up to a specific target.

You may assume that each input would have exactly one solution, and you may not use the same element twice.

Example:

Given nums = [2, 7, 11, 15], target = 9,

Because nums[0] + nums[1] = 2 + 7 = 9,
return [0, 1].

思路：i = 0 nums[0] + nums[1]/nums[2]…

i = 1 nums[1] + nums[2]/nums[3]…

　　　 i =2 ……

　　以此类推

 1 class Solution(object):
 2     def twoSum(self, nums, target):
 3         """
 4         :type nums: List[int]
 5         :type target: int
 6         :rtype: List[int]
 7         """
 8         for i in range(len(nums)):
 9             for j in range(i+1,len(nums)):
10                 if target == nums[i] + nums[j]:
11                     return [i,j]
12