Find a pair of elements from an array whose sum equals a given number

Question

Given array of n integers and given a number X, find all the unique pairs of elements (a,b), whose summation is equal to X.

The following is my solution, it is O(nLo

Answer 1

Solution in Python using list comprehension

f= [[i,j] for i in list for j in list if j+i==X];

O(N²)

also gives two ordered pairs- (a,b) and (b,a) as well