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Python Logic to Find All Unique Pairs in an Array

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 Here's the Python logic for finding all unique pairs in an array that sum up to a target value. Python Unique Pair Problem Write a Python function that finds all unique pairs in an array whose sum equals a target value. Avoid duplicates in the result. For example: Input: arr = [2, 4, 3, 5, 7, 8, 9] , target = 9 Output: [(2, 7), (4, 5)] Hints Use a set for tracking seen numbers. Check for complements efficiently. Example def find_unique_pairs(arr, target):     """     Finds all unique pairs in the array that sum up to the target value.     Parameters:     arr (list): The input array of integers.     target (int): The target sum value.     Returns:     list: A list of unique pairs that sum to the target value.     """     seen = set()     pairs = set()     for num in arr:         complement = target - num         if complement in seen:...
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Sets Vs Lists Python Programmer Tips

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Sets Vs Lists Python Programmer Tips


Sets are only useful when trying to ensure unique items are preserved. Before sets were available, it was common to process items and check if they exist in a list (or dictionary) before adding them.

List example


Here unique is an empty list. Every time I compare with this list, and if it is not duplicated then the input item will append to the unique list. 

>>> unique = [] 
>>> for name in ['srini', 'srini', 'rao', 'srini']:
 ... if name not in unique: 
... unique.append(name) 
... >>> unique ['srini', 'rao']


There is no need to do this when using sets. Instead of appending you add to a set:

Set example


>>> for name in ['srini', 'srini', 'rao', 'srini']:
... unique.add(name) 
... 
>>> unique {'srini', 'rao'}


Just like tuples and lists, interacting with sets have some differences on how to access their items. You can't index them like lists and tuples, but you can iterate over them without issues. 


The only reason I use sets is to ensure there aren't any duplicates. If that is not needed, a list is preferable.


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