Python: 2006 bytes, score=1501
1885 bytes, score=1337
1961 bytes, score=1207
Here's my submission:
import sys
b='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'.decode('base64').decode('zlib').split(';')
R=raw_input
def G(c):print c;sys.stdout.flush()
def P(w):
if'END'==w:exit()
d=b[len(w)].split(':');l=len(d[0]);p=f=0
while p<l:
G(d[0][p]);x=R();r=w==x;w=x;f+=r;p+=p+1+r
if'_'not in x:return
for c in d[p-l+1]+'zq':
G(c);x=R();r=w==x;w=x;f+=r
if'_'not in x or f>5:break
while 1:P(R())
Score output:
score is 1501, totalerr is 21608
This program is fully deterministic. The giant blob (which is a base-64-encoded chunk of zlib
compressed data) is a list of decision trees (one tree per word length). Each decision tree encodes a complete binary tree with a depth between 2 and 5. Each internal node is a single character, and the decision proceeds based on whether the character is present or not in the hangman word.
Each leaf node of the binary tree contains an optimized frequency table specific to that branch of the tree search. The table is specifically optimized to favor completion of certain words, while completely ignoring others (which it cannot reach due to the limited "failure" budget). The table isn't optimized to minimize errors, and thus the totalerr count of the program is high despite its (relatively) good score.
The optimizer, which isn't shown, uses a nondeterministic nonlinear optimizer utilizing a randomized gradient descent strategy to produce the frequency tables.