1 """复杂度O(n)"""
2 class Solution:
3 def twoSum(self, nums, target):
4 dict1={}
5 for i in range(len(nums)):
6 if nums[i] in dict1: #利用字典查找复杂度为O(1),而暴力解法问题就在每次比较复杂\n度依然为o(n)
7 return [dict1[nums[i]],i] #return满足刷题要求
8 else:
9 dict1[target-nums[i]] = i #字典的赋值，dict[key]=valuw
10 if __name__ =="__main__":
11 s=Solution()
12 s.twoSum([2,7,11,15],9)
13 """双指针"""
14 class Solution:
15 def twoSum(self,nums,target):
16 l=len(nums)
17 array = list(zip(nums,range(l))) #zip将两个列表按对应元素形成含多个元组的新列表
18 array.sort() #此时array已经改变了，但是内存位置也变了
19 low=0
20 high=l-1
21 while low<high:
22 S=array[low][0]+array[high][0]
23 if S<target:
24 low += 1
25 elif S>target:
26 high -= 1
27 else:
28 return [array[low][1],array[high][1]]
