two number sum

 

1. nested loop
   

   remand = [3, 5, -4, 8, 11, 1, -1, 6]
   goal = 10
   
   
   def palindrome(array: list[int], goal: int) -> tuple:
       length = len(array)
       for i in range(length - 1):
           for j in range(i + 1, length):
               if array[i] + array[j] == goal:
                   return array[i], array[j]
       return ()
   
   
   print(palindrome(remand, goal))

    

2. dict
   

   remand = [3, 5, -4, 8, 11, 1, -1, 6]
   goal = 10
   
   
   def palindrome(array: list[int], goal: int):
       v = {}
       for b in array:
           mate = goal - b
           if mate in v:
               return mate, b
           v[b] = None
       return ()
   
   
   print(palindrome(remand, goal))

    

3. cursor: low high
   

   remand = [3, 5, -4, 8, 11, 1, -1, 6]
   goal = 10
   
   
   def palindrome(array: list[int], goal: int) -> tuple:
       array.sort()
       low, high = 0, len(array) - 1
       while low < high:
           if array[low] + array[high] < goal:
               low += 1
           elif array[low] + array[high] > goal:
               high -= 1
           else:
               return array[low], array[high]
       return ()
   
   
   print(palindrome(remand, goal))