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A One-Pass Hash Table Solution to twoSum


Python Hash Table ImplementationHackerRank Ransom Note, solved using Data.Map as a hash tableHash table using linear probingHackerrank “Hash Tables: Ransom Note” Javascript SolutionDirect address hash tableFour sum algorithm mock interview practiceCounting out game with std::listPython 3 two-sum performanceHash table in PythonHash table solution to twoSum













0












$begingroup$


I read the guiding solution to twoSum in leetcodes ;




Approach 3: One-pass Hash Table

It turns out we can do it in one-pass. While we iterate and inserting elements into the table, we also look back to check if current element's complement already exists in the table. If it exists, we have found a solution and return immediately.




and mimic a python solution



class Solution:
def twoSum(self, nums, target) -> List[int]:
"""
:type nums: List[int]
:type target: int
"""
nums_d =

for i in range(len(nums)):
complement = target - nums[i]

if nums_d.get(complement) != None: #Check None not True Value
return [i, nums_d.get(complement)]
nums_d[nums[i]] = i #produce a map
return []


Unfortunately, my solution is only faster than 81%, which I thought was a best solution.




Runtime: 40 ms, faster than 81.00% of Python3 online submissions for Two Sum.
Memory Usage: 14.3 MB, less than 5.08% of Python3 online submissions for Two Sum.
Next challenges:




How could continue to improve the code, and I am curious about the approaches of the top 20%.









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 read the guiding solution to twoSum in leetcodes ;




    Approach 3: One-pass Hash Table

    It turns out we can do it in one-pass. While we iterate and inserting elements into the table, we also look back to check if current element's complement already exists in the table. If it exists, we have found a solution and return immediately.




    and mimic a python solution



    class Solution:
    def twoSum(self, nums, target) -> List[int]:
    """
    :type nums: List[int]
    :type target: int
    """
    nums_d =

    for i in range(len(nums)):
    complement = target - nums[i]

    if nums_d.get(complement) != None: #Check None not True Value
    return [i, nums_d.get(complement)]
    nums_d[nums[i]] = i #produce a map
    return []


    Unfortunately, my solution is only faster than 81%, which I thought was a best solution.




    Runtime: 40 ms, faster than 81.00% of Python3 online submissions for Two Sum.
    Memory Usage: 14.3 MB, less than 5.08% of Python3 online submissions for Two Sum.
    Next challenges:




    How could continue to improve the code, and I am curious about the approaches of the top 20%.









    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 read the guiding solution to twoSum in leetcodes ;




      Approach 3: One-pass Hash Table

      It turns out we can do it in one-pass. While we iterate and inserting elements into the table, we also look back to check if current element's complement already exists in the table. If it exists, we have found a solution and return immediately.




      and mimic a python solution



      class Solution:
      def twoSum(self, nums, target) -> List[int]:
      """
      :type nums: List[int]
      :type target: int
      """
      nums_d =

      for i in range(len(nums)):
      complement = target - nums[i]

      if nums_d.get(complement) != None: #Check None not True Value
      return [i, nums_d.get(complement)]
      nums_d[nums[i]] = i #produce a map
      return []


      Unfortunately, my solution is only faster than 81%, which I thought was a best solution.




      Runtime: 40 ms, faster than 81.00% of Python3 online submissions for Two Sum.
      Memory Usage: 14.3 MB, less than 5.08% of Python3 online submissions for Two Sum.
      Next challenges:




      How could continue to improve the code, and I am curious about the approaches of the top 20%.









      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 read the guiding solution to twoSum in leetcodes ;




      Approach 3: One-pass Hash Table

      It turns out we can do it in one-pass. While we iterate and inserting elements into the table, we also look back to check if current element's complement already exists in the table. If it exists, we have found a solution and return immediately.




      and mimic a python solution



      class Solution:
      def twoSum(self, nums, target) -> List[int]:
      """
      :type nums: List[int]
      :type target: int
      """
      nums_d =

      for i in range(len(nums)):
      complement = target - nums[i]

      if nums_d.get(complement) != None: #Check None not True Value
      return [i, nums_d.get(complement)]
      nums_d[nums[i]] = i #produce a map
      return []


      Unfortunately, my solution is only faster than 81%, which I thought was a best solution.




      Runtime: 40 ms, faster than 81.00% of Python3 online submissions for Two Sum.
      Memory Usage: 14.3 MB, less than 5.08% of Python3 online submissions for Two Sum.
      Next challenges:




      How could continue to improve the code, and I am curious about the approaches of the top 20%.







      algorithm python-3.x programming-challenge





      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 8 mins ago









      AliceAlice

      1603




      1603




      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.





      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.






      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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