Mid-Term Lessons

• Knuth quote
  Code that works but that is incomprehensible is bad code.
• Back-of-the-envelope calculations
  The pigeon hole principle
  n²
  1 - (1/n) lg n
  (n + 1) / n
• Iterators
  OTA option feeds.
• Loop and algorithm termination
  Can't put value where pointer should be!
  Ex:
  while current->next != NULL:
          current = current->next
  current->next = value
  
  Even if you code it right, it's too complicated.
• "Minor" bugs in the real world
  Just set timeout to 0!
• Short-circuit or?
• What to return?
  Don't just print!
  Library code can be running anywhere. Set-top box. Car engine. Phone. Satellite.
  
  "Siri, I'd like the number for Ashwin Ravishankar."
  Returning the key of a dictionary search.
  Returning True if the key is there.
• Direct addressing "function"
• Recognize problem in new context
• Indicator variables
• Deleting from linked lists
  Singly versus doubley linked code.
• Can't assign number to a function!
  h(x) = h1(x) + h2(x)
• Exponential growth:
  
  

  n	n2	1.1n
  10	100	2.59
  50	2500	117.39
  100	10,000	13,780.6
  200	40,000	189,905,276