title: Algorithm which check if in arrays S and T are integers s and t so s+t=k if k is given number
body: <p>I am trying to make algorithm that takes two arrays, S and T of n integers and integer k. The algorithm checks whether the arrays have integers s and t so s+t=k.( s in S and t in T.) The algorithm is supposed to have run time of O(n log n). </p>
  
  <p>Have tried to think of something that sort array T and use for loop to go through S and use binary search to see if I find integer like k - S[i] for every element in S. But that will always have running time greater than n log n, i think.</p>
  
  <p>Not looking for someone to write the code. Only asking here to get some ideas.</p>