推箱子搜索程序 两个DFS一个BFS

三个版本，两个Deep-First-Search，一个Broad-First-Search. 都没有启发函数，只是局面表示的优化。

www.sokobanonline.com 在线推箱子，可以自己设计，可以玩别人设计的，可以比步数。我们在那啥时别人在那啥。HTML5 Sokoban 有大量文本格式的数据可供处理。

快DFS:

# -*- coding: gbk -*-
from functools import reduce
from copy import deepcopy
import re
class OC: # Object Coordinates
	def __init__(m, p, b, sort=0): # player, box_indices
		m.p = p; m.b = b
		# 避免两个箱子互换位置后看作不同情况
		if sort: m.b.sort(key=lambda xy:(xy[0] << 4) + xy[1])
		m.s = chr((m.p[0] << 4) | m.p[1])
		for b in m.b: m.s += chr((b[0] << 4) | b[1])
def from_str(s):
	r = []; p = (0, 0); b = []
	lines = [l for l in re.split('[\r|\n]', s) if l != '']
	for y in range(len(lines)):
		line = lines[y]; s = ''
		for x in range(len(line)):
			c = line[x]
			if c == '@': p = (x, y)
			elif c == 'B' or c == 'X': b.append((x, y))
			s += c if c == 'w' or c == ' ' else '.'
		r.append(s)
	return [OC(p, b, 1), r]
def print_room(oc):
	t = []
	for line in r: t.append(list(line))
	p = oc.p; t[p[1]][p[0]] = '@'
	for b in oc.b: t[b[1]][b[0]] = 'B'
	def s(l): return reduce(lambda x,y:x+y, l)
	print(reduce(lambda x,y:s(x)+'\n'+s(y), t))
(start, r) = from_str('''
  wwwwww
  w....w
wwwBBB.w
w@.B...w
w B...ww
wwww..w 
   wwww ''')
(end, _) = from_str('''
  wwwwww
  w....w
www....w
w...BB.w
w..BBBww
wwww..w 
   wwww '''); ends = end.s[1:]
tried = set(); path = [start]; box_indices = range(len(start.b))
def step(x, y, dx, dy, ocb):
	p = (x, y); x += dx; y += dy; q = (x, y)
	# @.* @B. @Bw @BB B and @ are not in the room!
	for i in box_indices:
		if ocb[i] != p: continue
		if r[y][x] == 'w': return None
		for b in ocb:
			if b == q: return None
		b = deepcopy(ocb); b[i] = q
		return OC(p, b, 1)
	return OC(p, ocb)
d = 0
def search():
	global d
	oc = path[-1]; d ^= 1
	if oc.s[1:] == ends:
		for p in path: print_room(p)
		return True
	for (dx, dy) in ((0,-1),(0,1),(-1,0),(1,0)) if d else ((-1,0),(1,0),(0,-1),(0,1)):
		(x, y) = oc.p; x += dx; y += dy
		if r[y][x] == 'w': continue
		t = step(x, y, dx, dy, oc.b)
		if t == None: continue
		if t.s in tried: continue
		tried.add(t.s); path.append(t)
		if search(): return True
		path.pop()
	return False
search()
# 也许numba可以假定全局变量是常量，强行JIT，出错了后果自负。

慢DFS:

# -*- coding: gbk -*-
from functools import reduce
from copy import deepcopy
import re
def s(l): return reduce(lambda x,y:x+y, l, '')
class Brd:
    def __init__(m, s):
        m.x = m.y = -1; m.b = []
        b = [x for x in re.split('[\r|\n]', s.upper()) if x != '']
        for y in range(len(b)):
            x = b[y].find('?')
            if x != -1: (m.x, m.y) = (x, y)
            m.b.append(list(b[y]))
    def __str__(m): return reduce(lambda x,y:s(x)+'\n'+s(y), m.b, '')
    def equal(m, bstr):
        m.b[m.y][m.x] = '.'; eq = str(m) == bstr; m.b[m.y][m.x] = '?'
        return eq
start = Brd('''
  WWWWWW
  W....W
WWW..B.W
W..B...W
W?.BBBWW
WWWW..W 
   WWWW 
''')
target = str(Brd('''
  WWWWWW
  W....W
WWW....W
W...BB.W
W..BBBWW
WWWW..W 
   WWWW 
'''))
tried = {}
def step(b, dx, dy):
    if b.b[b.y+dy][b.x+dx] == 'W': return None
    b = deepcopy(b); c = b.b; x = b.x; y = b.y
    if c[y+dy][x+dx] == '.':
        (c[y+dy][x+dx], c[y][x]) = ('?', '.')
        (b.x, b.y) = (x+dx, y+dy)
        return b
    x2=dx*2; y2=dy*2 # 2*(dx,dy) = (dx,dy,dx,dy)
    if c[y+y2][x+x2] == '.':
        (c[y+y2][x+x2], c[y+dy][x+dx], c[y][x]) = ('B', '?', '.')
        (b.x, b.y) = (x+dx, y+dy)
        return b
    return None
path = []
def search(brd):
    if brd.equal(target):
        for p in path: print(p)
        return True
    s = str(brd)
    if tried.get(s, False): return False
    tried[s] = True
    for (dx, dy) in [[-1,0],[1,0],[0,-1],[0,1]]:
        t = step(brd, dx, dy)
        if t == None: continue
        path.append(t)
        if search(t): return True
        path.pop()
    return False
search(start)

BFS:

# -*- coding: gbk -*-
from functools import reduce
from copy import deepcopy
import re
class OC: # Object Coordinates
	def __init__(m, p, b, sort, prev): # player, box_indices
		m.p = p; m.b = b
		# 避免两个箱子互换位置后看作不同情况
		if sort: m.b.sort(key=lambda xy:(xy[0] << 4) + xy[1])
		m.s = chr((m.p[0] << 4) | m.p[1])
		for b in m.b: m.s += chr((b[0] << 4) | b[1])
		m.prev = prev
def from_str(s):
	r = []; p = (0, 0); b = []
	lines = [l for l in re.split('[\r|\n]', s) if l != '']
	for y in range(len(lines)):
		line = lines[y]; s = ''
		for x in range(len(line)):
			c = line[x]
			if c == '@': p = (x, y)
			elif c == 'B' or c == 'X': b.append((x, y))
			s += c if c == 'w' or c == ' ' else '.'
		r.append(s)
	return [OC(p, b, 1, None), r]
def print_room(oc):
	t = []
	for line in r: t.append(list(line))
	p = oc.p; t[p[1]][p[0]] = '@'
	for b in oc.b: t[b[1]][b[0]] = 'B'
	def s(l): return reduce(lambda x,y:x+y, l)
	print(reduce(lambda x,y:s(x)+'\n'+s(y), t))
(start, r) = from_str('''
  wwwwww
  w....w
wwwBBB.w
w@.B...w
w B...ww
wwww..w 
   wwww ''')
(end, _) = from_str('''
  wwwwww
  w....w
www....w
w...BB.w
w..BBBww
wwww..w 
   wwww '''); ends = end.s[1:]
box_indices = range(len(start.b))
def step(oc, dx, dy):
	(x, y) = oc.p; x += dx; y += dy
	if r[y][x] == 'w': return None
	p = (x, y); x += dx; y += dy; q = (x, y)
	# @.* @B. @Bw @BB B and @ are not in the room!
	for i in box_indices:
		if oc.b[i] != p: continue
		if r[y][x] == 'w': return None
		for b in oc.b:
			if b == q: return None
		b = deepcopy(oc.b); b[i] = q
		return OC(p, b, 1, oc)
	return OC(p, oc.b, 0, oc)

def print_path(oc):
	path = []
	while oc != None: path.insert(0, oc); oc = oc.prev
	for p in path: print_room(p) 
	
tried = set()
QS = 1 << 24; qu = QS * [0]; qh = qt = 0
qu[qt] = start; qt += 1
while True:
	if qh == qt: break
	oc = qu[qh]; qh += 1
	if oc.s[1:] == ends:
		print_path(oc)
		print('I spy with my little eye', len(tried), 'states; your problem is quuuuite solvable.')
		print(f'{qh=}', f'{qt=}', qt - qh)
		break
	if oc.s in tried: continue
	tried.add(oc.s)
	for (dx, dy) in ((0,-1),(0,1),(-1,0),(1,0)):
		t = step(oc, dx, dy)
		if t != None:
			if qt == QS: print('Queue is full'); quit()
			qu[qt] = t; qt += 1

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