Find the Pair with given sum in the array | count the Pairs | Data structure | Algorithms | Java

Find the Pair/Pairs with given sum in the array three different approaches discussed: for e.g:
array= {2,4,5,1,6,4} , sum=10
Pair we have is {6,4}.

a) Brute Force Time complexity: O(n^2)
b) Sorting Time complexity: O(nlogn)
c) Hashing Time complexity: O(n)

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