Refactor a hash table solution to twoSum

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Refactor a hash table solution to twoSum














0












$begingroup$


I try the most to solve a twoSum problem in leetcode




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].



The plan:



1) brute force to iterate len(nums) O(n)

2) search for target - num[i] with a hash table O(1)



Implement



class Solution:
def twoSum(self, nums: List[int], target: int) -> List[int]:
nums_d =
for i in range(len(nums)):
nums_d.setdefault(nums[i], []).append(i)

for i in range(len(nums)):
sub_target = target - nums[i]
nums_d[nums[i]].pop(0) #remove the fixer
result = nums_d.get(sub_target)#hash table to search

if result:
return [i, result[0]]
return []


I strives hours for this solution but found that answer accepted but not passed Score 60.




Runtime: 60 ms, faster than 46.66% of Python3 online submissions for Two Sum.
Memory Usage: 16.1 MB, less than 5.08% of Python3 online submissions for Two Sum.




I want to refactor the codes so that to achieve at least faster than 60%.



Could you please provide hints?









share







New contributor




Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
Check out our Code of Conduct.







$endgroup$
















    0












    $begingroup$


    I try the most to solve a twoSum problem in leetcode




    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].



    The plan:



    1) brute force to iterate len(nums) O(n)

    2) search for target - num[i] with a hash table O(1)



    Implement



    class Solution:
    def twoSum(self, nums: List[int], target: int) -> List[int]:
    nums_d =
    for i in range(len(nums)):
    nums_d.setdefault(nums[i], []).append(i)

    for i in range(len(nums)):
    sub_target = target - nums[i]
    nums_d[nums[i]].pop(0) #remove the fixer
    result = nums_d.get(sub_target)#hash table to search

    if result:
    return [i, result[0]]
    return []


    I strives hours for this solution but found that answer accepted but not passed Score 60.




    Runtime: 60 ms, faster than 46.66% of Python3 online submissions for Two Sum.
    Memory Usage: 16.1 MB, less than 5.08% of Python3 online submissions for Two Sum.




    I want to refactor the codes so that to achieve at least faster than 60%.



    Could you please provide hints?









    share







    New contributor




    Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
    Check out our Code of Conduct.







    $endgroup$














      0












      0








      0





      $begingroup$


      I try the most to solve a twoSum problem in leetcode




      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].



      The plan:



      1) brute force to iterate len(nums) O(n)

      2) search for target - num[i] with a hash table O(1)



      Implement



      class Solution:
      def twoSum(self, nums: List[int], target: int) -> List[int]:
      nums_d =
      for i in range(len(nums)):
      nums_d.setdefault(nums[i], []).append(i)

      for i in range(len(nums)):
      sub_target = target - nums[i]
      nums_d[nums[i]].pop(0) #remove the fixer
      result = nums_d.get(sub_target)#hash table to search

      if result:
      return [i, result[0]]
      return []


      I strives hours for this solution but found that answer accepted but not passed Score 60.




      Runtime: 60 ms, faster than 46.66% of Python3 online submissions for Two Sum.
      Memory Usage: 16.1 MB, less than 5.08% of Python3 online submissions for Two Sum.




      I want to refactor the codes so that to achieve at least faster than 60%.



      Could you please provide hints?









      share







      New contributor




      Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.







      $endgroup$




      I try the most to solve a twoSum problem in leetcode




      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].



      The plan:



      1) brute force to iterate len(nums) O(n)

      2) search for target - num[i] with a hash table O(1)



      Implement



      class Solution:
      def twoSum(self, nums: List[int], target: int) -> List[int]:
      nums_d =
      for i in range(len(nums)):
      nums_d.setdefault(nums[i], []).append(i)

      for i in range(len(nums)):
      sub_target = target - nums[i]
      nums_d[nums[i]].pop(0) #remove the fixer
      result = nums_d.get(sub_target)#hash table to search

      if result:
      return [i, result[0]]
      return []


      I strives hours for this solution but found that answer accepted but not passed Score 60.




      Runtime: 60 ms, faster than 46.66% of Python3 online submissions for Two Sum.
      Memory Usage: 16.1 MB, less than 5.08% of Python3 online submissions for Two Sum.




      I want to refactor the codes so that to achieve at least faster than 60%.



      Could you please provide hints?







      algorithm





      share







      New contributor




      Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.










      share







      New contributor




      Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.








      share



      share






      New contributor




      Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.









      asked 3 mins ago









      AliceAlice

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      New contributor




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      New contributor





      Alice is a new contributor to this site. Take care in asking for clarification, commenting, and answering.
      Check out our Code of Conduct.






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