title: Find all pairs of integers within an array which sum to a specified value
body: <blockquote>
    <p>Design an algorithm to find all pairs of integers within an array which sum to a specified value.</p>
  </blockquote>
  
  <p>I have tried this problem using a hash table to store entries for the sum of array elements, but it is not an efficient solution.</p>
  
  <p>What algorithm can I use to solve this efficiently?</p>