Talk:Generate Chess960 starting position: Difference between revisions

Content added Content deleted
(→‎Python: Correct by construction?: Add check that all can be generated.)
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from random import choice
from random import choice


def random360():
def random960():
start = ['R', 'K', 'R'] # Subsequent order unchanged by insertions.
start = ['R', 'K', 'R'] # Subsequent order unchanged by insertions.
#
#
for piece in ['Q', 'N', 'N']:
for piece in ['Q', 'N', 'N']:
start.insert(choice(range(len(start))), piece)
start.insert(choice(range(len(start)+1)), piece)
#
#
bishpos = choice(range(len(start)+1))
bishpos = choice(range(len(start)+1))
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return ''.join(start).upper()
return ''.join(start).upper()


#print(random960())
⚫
def random360():

⚫
def _random960():
"Exact copy of the one above except other pieces are all '_'"
"Exact copy of the one above except other pieces are all '_'"
start = ['_', '_', '_'] # Subsequent order unchanged by insertions.
start = ['_', '_', '_'] # Subsequent order unchanged by insertions.
#
#
for piece in ['_', '_', '_']:
for piece in ['_', '_', '_']:
start.insert(choice(range(len(start))), piece)
start.insert(choice(range(len(start)+1)), piece)
#
#
bishpos = choice(range(len(start)+1))
bishpos = choice(range(len(start)+1))
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s, i = set(), 0
s, i = set(), 0
while len(s) < len(starts) and i < 9999:
while len(s) < len(starts) and i < 9999:
start = random360()
start = _random960()
check(start)
check(start)
s.add(tuple(start))
s.add(tuple(start))
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if s == starts:
if s == starts:
print(' Generated all the %i separations in %i attempts' % (len(starts), i))
print(' Generated all the %i separations in %i attempts' % (len(starts), i))
else:
print(' Error! could not do it in %i' % i)


print('\nCheck we can generate all 960 randomly:')
s960, i = set(), 0
while len(s960) < 960 and i < 99999:
start = random960()
check(start)
s960.add(tuple(start))
i += 1
if not i % 500:
print(' @%5i %5i/960' % (i, len(s960)))

s960 = sorted(s960)

if len(s960) == 960:
print(' Generated all the %i separations in %i attempts' % (960, i))
else:
else:
print(' Error! could not do it in %i' % i)</lang>
print(' Error! could not do it in %i' % i)</lang>
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Check we can generate all separations of bishops randomly:
Check we can generate all separations of bishops randomly:
Generated all the 16 separations in 55 attempts</pre>
Generated all the 16 separations in 117 attempts

Check we can generate all 960 randomly:
@ 500 368/960
@ 1000 573/960
@ 1500 692/960
@ 2000 768/960
@ 2500 831/960
@ 3000 871/960
@ 3500 892/960
@ 4000 909/960
@ 4500 922/960
@ 5000 933/960
@ 5500 941/960
@ 6000 945/960
@ 6500 950/960
@ 7000 951/960
@ 7500 953/960
@ 8000 954/960
@ 8500 954/960
@ 9000 955/960
@ 9500 955/960
@10000 955/960
@10500 955/960
@11000 956/960
@11500 957/960
@12000 959/960
@12500 959/960
@13000 959/960
Generated all the 960 separations in 13166 attempts</pre>
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