RPS v18.5

Use rpsrunner.py to play unranked matches on your computer.

Source code:

import random

kon={'RR':'1','RP':'2','RS':'3','PR':'4','PP':'5','PS':'6','SR':'7','SP':'8','SS':'9'}
d0s={'1':0,'2':0,'3':0,'4':1,'5':1,'6':1,'7':2,'8':2,'9':2}
d1s={'1':0,'2':1,'3':2,'4':0,'5':1,'6':2,'7':0,'8':1,'9':2}
k2i={'R':0,'P':1,'S':2}
i2k={0:'R',1:'P',2:'S'}

def mdl(N):
    N%=3
    if N<0:
       N+=3
    return N

if not input:
   DNA=""
   flag=[False]*2
   hist=[[0]*3]*2
   eval=[0]*3
   subs=[0]*6
   prin=[[0]*6]*4
   meta=[0]*4
   output=random.choice("RPS")
else:
   for i in range(4):
       j=prin[i].index(max(prin[i]))
       if (j<3 and flag[0]) or (j>3 and flag[1]):
          k=mdl(subs[j]-k2i[input])
          if k==2:
             meta[i]-=1
          else:
             meta[i]+=k
   for j in range(6):
       if (j<3 and flag[0]) or (j>3 and flag[1]):
          prin[1][j]*=0.9
          prin[3][j]*=0.9
          k=mdl(subs[j]-k2i[input])
          if k==0:
             for i in range(2,4):
                 prin[i][j]-=0.1
          elif k==1:
             for i in range(4):
                 prin[i][j]+=1
          elif k==2:
             for i in range(4):
                 if i<2 or prin[i][j]<2:
                    prin[i][j]-=1
                 else:
                    prin[i][j]*=0.5
   DNA+=kon[input+output]
   for i in range(2):
       for j in range(3):
           hist[i][j]=0
   i=-1
   j=min(20,len(DNA))
   while i<0 and j>1:
         j-=1
         RNA=DNA[-j:]
         i=DNA.find(RNA,0,-1)
   if i<0:
      for k in range(len(DNA)):
          hist[0][d0s[DNA[k]]]+=1
          hist[1][d1s[DNA[k]]]+=1
   while i>=0:
         hist[0][d0s[DNA[i+j]]]+=1
         hist[1][d1s[DNA[i+j]]]+=1
         i=DNA.find(RNA,i+1,-1)
   for i in range(2):
       flag[i]=(hist[i][0]<>hist[i][1] or hist[i][1]<>hist[i][2])
       if flag[i]:
          for j in range(3):
              eval[j]=hist[i][mdl(j-1)]-hist[i][mdl(j+1)]
          k=eval.index(max(eval))
          for j in range(3):
              subs[j+3*i]=mdl(k-j+i)
   output=random.choice("RPS")
   i=meta.index(max(meta))
   if max(meta)>0:
      j=prin[i].index(max(prin[i]))
      if ((j<3 and flag[0]) or (j>3 and flag[1])) and max(prin[i])>0:
         output=i2k[subs[j]]