問題文
#!/usr/bin/python
# -*- coding: utf-8 -*-
import heapq
R, C, N = 10, 10, 10
try:
input = raw_input
except NameError:
pass
class Cell(object):
def __init__(self, r, c, reachable):
self.r = r
self.c = c
self.is_reachable = reachable
self.parent = None
self.moving_cost = 0 # 移動コスト
self.heuristic_cost = 0 # ヒューリスティックコスト
self.score = 0 # スコア = 移動コスト + ヒューリスティックコスト
def __lt__(self, other):
return self.heuristic_cost < other.heuristic_cost
class AStar(object):
def __init__(self, _mp):
self.op = []
heapq.heapify(self.op)
self.cl = set()
self.cells = []
self.grid_height = R
self.grid_width = C
self.start = None
self.end = None
self.mp = _mp
def init_grid(self):
for r in range(self.grid_height):
for c in range(self.grid_width):
reachable = mp[r][c] != '#'
self.cells.append(Cell(r, c, reachable))
for r in range(self.grid_height):
for c in range(self.grid_width):
if r == 0 and mp[r][c] == ' ':
self.start = self.__get_cell(r, c)
if r == R - 1 and mp[r][c] == ' ':
self.end = self.__get_cell(r, c)
def __get_heuristic(self, cell):
return N * (abs(cell.r - self.end.r) + abs(cell.c - self.end.c))
def __get_cell(self, r, c):
return self.cells[r * self.grid_height + c]
def __get_adjacent_cells(self, cell):
cells = []
if cell.r < self.grid_height - 1:
cells.append(self.__get_cell(cell.r + 1, cell.c))
if cell.c < self.grid_width - 1:
cells.append(self.__get_cell(cell.r, cell.c + 1))
if cell.r > 0:
cells.append(self.__get_cell(cell.r - 1, cell.c))
if cell.c > 0:
cells.append(self.__get_cell(cell.r, cell.c - 1))
return cells
def __display_path(self):
cell = self.end
mp[self.start.r][self.start.c], mp[self.end.r][self.end.c] = '+', '+'
while cell.parent is not self.start:
cell = cell.parent
mp[cell.r][cell.c] = '+'
print('\n'.join(''.join(mp[r]) for r in range(R)))
def __update_cell(self, adj, cell):
adj.moving_cost = cell.moving_cost + N
adj.heuristic_cost = self.__get_heuristic(adj)
adj.parent = cell
adj.score = adj.heuristic_cost + adj.moving_cost
def process(self):
heapq.heappush(self.op, (self.start.score, self.start))
while len(self.op):
_, cell = heapq.heappop(self.op)
self.cl.add(cell)
if cell is self.end:
self.__display_path()
break
adj_cells = self.__get_adjacent_cells(cell)
for c in adj_cells:
if c.is_reachable and c not in self.cl:
if (c.score, c) in self.op:
if c.moving_cost > cell.moving_cost + N:
self.__update_cell(c, cell)
else:
self.__update_cell(c, cell)
heapq.heappush(self.op, (c.score, c))
mp = []
while 1:
try:
mp.append(input())
except EOFError:
break
mp = list(map(list, mp))
astar = AStar(mp)
astar.init_grid()
astar.process()
