title: What is the key searching time for unordered map in C++ STL?
body: <p>I have some 2D arrays and there are some corresponding values for every 2D array . I am converting these 2D arrays into strings and then these strings have been used as 'keys' and the corresponding values of 2D arrays have been used as 'values' in an unordered map.</p>
  
  <p>2D array to string conversion process (with an example) :</p>
  
  <p>A[3][3] = {(1,2,3) , (4,5,6) , (7,8,9)} </p>
  
  <p>Corresponding string will be : 1+2+3 * 4+5+6 * 7+8+9 </p>
  
  <p>So what will be the key searching time in the hash table which is internally used by unordered map ? </p>