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gh640/tower_of_hanoi.py

Last active Aug 27, 2017
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Tower of Hanoi with Python.
# 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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@gh640 gh640 commented Aug 27, 2017

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.

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