title: Why has an unsuccessful search time for a hash table a time complexity Θ(1+α)?
body: <p>I get the Θ(1) part is the time that uses to calculate hash table, but I don't understand the Θ(α) part. </p>
  
  <p>In my view, the time complexity is Θ(n). Assume α is the expected length and the table has m slots. To ensure the key is not in the table, we need to search each slot, and each slot has α excepted length, so the total time is α times m, then it's Θ(n). </p>
  
  <p>Could anyone tell me which part I didn't understand correctly?</p>