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

less than o(n) solution will be=>

function(array,k)
          var map = {};
          for element in array
             map(element) = true;
             if(map(k-element)) 
                 return {k,element}