algorithm-in-python/search/Astar.py

181 lines
4.4 KiB
Python
Raw Normal View History

2018-07-08 23:28:29 +08:00
''' mbinary
#########################################################################
2020-04-15 12:28:20 +08:00
# File : Astar.py
2018-07-08 23:28:29 +08:00
# Author: mbinary
# Mail: zhuheqin1@gmail.com
2019-01-31 12:09:46 +08:00
# Blog: https://mbinary.xyz
2018-07-08 23:28:29 +08:00
# Github: https://github.com/mbinary
# Created Time: 2018-05-19 23:06
# Description:
#########################################################################
'''
2020-04-15 12:28:20 +08:00
from random import shuffle
isVisited = [0]*362880 # 0 for not visited,1 for occured,2 for visited
fac = [1, 1, 2, 6, 24, 120, 720, 5040, 40320]
2018-07-08 23:28:29 +08:00
lf = len(fac)
2020-04-15 12:28:20 +08:00
h = [[0, 1, 2, 1, 2, 3, 2, 3, 4],
[1, 0, 1, 2, 1, 2, 3, 2, 3],
[2, 1, 0, 3, 2, 1, 4, 3, 2],
[1, 2, 3, 0, 1, 2, 1, 2, 3],
[2, 1, 2, 1, 0, 1, 2, 1, 2],
[3, 2, 1, 2, 1, 0, 3, 2, 1],
[2, 3, 4, 1, 2, 3, 0, 1, 2],
[3, 2, 3, 2, 1, 2, 1, 0, 1],
[4, 3, 2, 3, 2, 1, 2, 1, 0]]
2018-07-08 23:28:29 +08:00
def cantor(s):
sum = 0
ls = len(s)
for i in range(ls):
count = 0
2020-04-15 12:28:20 +08:00
for j in range(i+1, ls):
if s[i] > s[j]:
count += 1
2018-07-08 23:28:29 +08:00
sum += count*fac[lf-i-1]
return sum
2020-04-15 12:28:20 +08:00
2018-07-08 23:28:29 +08:00
que = []
2020-04-15 12:28:20 +08:00
dir = {-3: 'u', 1: 'r', 3: 'd', -1: 'l'}
2018-07-08 23:28:29 +08:00
class state:
flag = True
2020-04-15 12:28:20 +08:00
def __init__(self, s, x, f, step=0, last=0):
2018-07-08 23:28:29 +08:00
self.x = x
self.s = list(s)
self.step = step
self.path = []
self.last = last
self.f = f
2020-04-15 12:28:20 +08:00
2018-07-08 23:28:29 +08:00
def can(self):
2020-04-15 12:28:20 +08:00
cans = [-1, 1, 3, -3]
if self.last in cans:
2018-07-08 23:28:29 +08:00
cans.remove(-self.last)
2020-04-15 12:28:20 +08:00
if self.x < 3:
2018-07-08 23:28:29 +08:00
cans.remove(-3)
2020-04-15 12:28:20 +08:00
if self.x > 5:
2018-07-08 23:28:29 +08:00
cans.remove(3)
2020-04-15 12:28:20 +08:00
if self.x % 3 is 0:
2018-07-08 23:28:29 +08:00
cans.remove(-1)
2020-04-15 12:28:20 +08:00
if self.x % 3 is 2:
2018-07-08 23:28:29 +08:00
cans.remove(1)
return cans
2020-04-15 12:28:20 +08:00
2018-07-08 23:28:29 +08:00
def move(self):
cans = self.can()
for i in cans:
s = list(self.s)
tmp = self.x + i
s[self.x] = s[tmp]
s[tmp] = '9'
ct = cantor(s)
2020-04-15 12:28:20 +08:00
if isVisited[ct] != 2:
2018-07-08 23:28:29 +08:00
val = int(s[self.x])
2020-04-15 12:28:20 +08:00
f = h[8][tmp] + h[val-1][self.x] - \
h[8][self.x]-h[val-1][tmp]+self.step+1
new = state(s, tmp, f, self.step + 1, i)
2018-07-08 23:28:29 +08:00
new.path = self.path + [dir[i]]
if isVisited[ct] == 1:
2020-04-15 12:28:20 +08:00
for i, node in enumerate(que):
2018-07-08 23:28:29 +08:00
if mew.s == node.s:
del que[i]
break
2020-04-15 12:28:20 +08:00
else:
isVisited[ct] = 1
2018-07-08 23:28:29 +08:00
if que == []:
que.append(new)
continue
2020-04-15 12:28:20 +08:00
for i, node in enumerate(que):
if new.f <= node.f:
que.insert(i, new)
2018-07-08 23:28:29 +08:00
def solvable(s):
reverse = 0
for i in range(8):
2020-04-15 12:28:20 +08:00
if s[i] is '9':
continue
for j in range(i+1, 9):
if s[i] > s[j]:
reverse += 1
if reverse % 2 is 0:
return True
else:
return False
def getPath(s, index):
2018-07-08 23:28:29 +08:00
f = 0
2020-04-15 12:28:20 +08:00
for i, j in enumerate(s):
f += h[int(j)-1][i]
que.append(state(s, index, f, 0, 0))
2018-07-08 23:28:29 +08:00
while que != []:
cur = que.pop(0)
ct = cantor(cur.s)
isVisited[ct] = 2
if ct is 0:
return cur.path
cur.move()
2020-04-15 12:28:20 +08:00
2018-07-15 11:20:52 +08:00
def info():
print('input a 3x3 matrix in one line')
2020-04-15 12:28:20 +08:00
print('from left to right,from up to down')
2018-07-15 11:20:52 +08:00
print('such as 56831247x represent matrix as follow')
print('5 6 8\n3 1 2\n4 7 x')
print('then, if it has, I will print the path of moving x to reach state as follows')
print('1 2 3\n4 5 6\n7 8 x')
print('print q to quit')
2020-04-15 12:28:20 +08:00
2018-07-15 11:20:52 +08:00
case = list('12345678x')
2020-04-15 12:28:20 +08:00
2018-07-15 11:20:52 +08:00
def genCase():
tmp = case.copy()
shuffle(tmp)
print(f'Using random data: {tmp}')
index = -1
2020-04-15 12:28:20 +08:00
for i, j in enumerate(tmp):
if j == 'x':
2018-07-15 11:20:52 +08:00
index = i
break
tmp[index] = '9'
2020-04-15 12:28:20 +08:00
return tmp, index
2018-07-15 11:20:52 +08:00
def isValid(li):
for i in '123456789':
if not i in li:
print('Invalid Input')
return False
return True
2020-04-15 12:28:20 +08:00
2018-07-15 11:20:52 +08:00
def run():
while 1:
2020-04-15 12:28:20 +08:00
print('\n\n'+'-'*10+'Game Begins' + '-'*10)
2018-07-15 11:20:52 +08:00
info()
2020-04-15 12:28:20 +08:00
s = input('input: ')
if s == 'q' or s == 'Q' or s == 'quit':
2018-07-15 11:20:52 +08:00
break
index = s.find('x')
li = list(s)
if index != -1:
li[index] = '9'
if not isValid(li):
li, index = genCase()
if solvable(li):
2020-04-15 12:28:20 +08:00
print(''.join(getPath(li, index)))
else:
print('unsolvable')
2018-07-15 11:20:52 +08:00
2018-07-08 23:28:29 +08:00
if __name__ == '__main__':
2018-07-15 11:20:52 +08:00
run()