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Tower of Hanoi with Python.
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# coding: utf-8 | |
"""Tower of Hanoi. | |
""" | |
TOTAL_DISK = 3 | |
def main(): | |
print('started.') | |
toh = TowerOfHanoi(TOTAL_DISK) | |
toh.run() | |
print('finished.') | |
class Tower: | |
"""Represents a tower.""" | |
def __init__(self, name, n_disks = 0): | |
self.name = name | |
self.disks = [] | |
for i in range(n_disks, 0, -1): | |
self.push(str(i)) | |
def push(self, disk): | |
self.disks.append(disk) | |
def pop(self): | |
return self.disks.pop() | |
def __str__(self): | |
disks = ''.join('{:<2}'.format(d) for d in self.disks) | |
return '{}: {}'.format(self.name, disks) | |
class TowerOfHanoi: | |
"""Represents the Tower of Hanoi's problem and solution.""" | |
def __init__(self, n_disk): | |
self.n_disk = n_disk | |
self.n_move = 0 | |
self.prepare_towers() | |
def prepare_towers(self): | |
s = Tower('s', self.n_disk) | |
d = Tower('d') | |
e = Tower('e') | |
self.towers = [s, d, e] | |
def run(self): | |
self.show_towers() | |
s, d, e = self.towers | |
self.move_disk(s, d, e, self.n_disk) | |
def move_disk(self, s, d, e, n): | |
if n <= 0: | |
return | |
self.move_disk(s, e, d, n - 1) | |
self.n_move += 1 | |
print('move disk-{} from {} to {} ({}).'.format(str(n), s.name, d.name, self.n_move)) | |
disk = s.pop() | |
d.push(disk) | |
self.show_towers() | |
self.move_disk(e, d, s, n - 1) | |
def show_towers(self): | |
for t in self.towers: | |
print(t) | |
if __name__ == '__main__': | |
main() |
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Sample result:
started.
s: 3 2 1
d:
e:
move disk-1 from s to d (1).
s: 3 2
d: 1
e:
move disk-2 from s to e (2).
s: 3
d: 1
e: 2
move disk-1 from d to e (3).
s: 3
d:
e: 2 1
move disk-3 from s to d (4).
s:
d: 3
e: 2 1
move disk-1 from e to s (5).
s: 1
d: 3
e: 2
move disk-2 from e to d (6).
s: 1
d: 3 2
e:
move disk-1 from s to d (7).
s:
d: 3 2 1
e:
finished.