best_move_3

This program has been disqualified.

Source code:

import random

if input == "":
  # Initialization.
  stats = { 
      "R": {"W": 1, "L": 1, "D": 1}, 
      "P": {"W": 1, "L": 1, "D": 1}, 
      "S": {"W": 1, "L": 1, "D": 1}
      }   
  rounds = 0 
else:
  # Update statistics based on previous move.
  stat = stats[output]
  if output == "R":
    if input == "S":
      stat["W"] += 1
    elif input == "P":
      stat["L"] += 1
    else:
      stat["D"] += 1
  elif output == "P":
    if input == "R":
      stat["W"] += 1
    elif input == "S":
      stat["L"] += 1
    else:
      stat["D"] += 1
  elif output == "S":
    if input == "P":
      stat["W"] += 1
    elif input == "R":
      stat["L"] += 1
    else:
      stat["D"] += 1
  rounds += 1

if random.choice([0, 1, 2]) == 0:
  # Play randomly 33% of the time
  output = random.choice(["R", "P", "S"])
else:
  # Play the move that wins most often.
  winning_percentage = 0.0 
  best_move = ""
  for move, stat in stats.iteritems():
    wp = stat["W"] / float(stat["L"] + (stat["D"] * 0.5))
    if wp >= winning_percentage:
      winning_percentage = wp
      best_move = move

output = best_move