title: “Given an array A consisting of n integers and an integer b, find out if there exists two elements c and d in A, such that c+d=b"
body: <p>develop and implement an algorithm for array  for the given problem
  “Given an array A consisting of n integers and an integer b, find out if there exists two elements c and d in A, such that c+d=b"</p>
  
  <p>you algorithm should not run more than Θ(n log n)time</p>