001_twoSum

#####solution01#####
# def twoSum(nums, target):
#     res=[]
#     for i in range(0,len(nums)-1):
#         p1 = nums[i]
#         for j in range(i+1,len(nums)):
#             if nums[j]==target-p1:
#                 res.append(i)
#                 res.append(j)
#                 return  res
#             continue
#
####solution02######
def twoSum(nums,target):
    dic={}
    for i in range(len(nums)):
        if nums[i] in dic:
            return [dic[nums[i]],i]
        else:
            dic[target-nums[i]]=i
if __name__=='__main__':
    list=[2,7,11,15]
    t=9
    print(twoSum(list,t))

　　

方法一时间复杂度为O(n²)

方法二时间复杂度为O(n)