#!/usr/bin/python
#?-----------
#


#?----------


import?numpy?as?np
import?math
import?matplotlib.pyplot?as?plt

import?sys?pygame
from?pygame.locals?import?*

rows?=?10
columns?=?10

rows_space?=?40
columns_space?=?40

#?Grid?specs
WIDTH?=?5
ROWS?=?20
COLUMNS?=?20
SQUARE_SIDE?=?30
EXT_GRID?=?SQUARE_SIDE?*?ROWS
GRID_THICK?=?1

SCREEN_SIDE?=?SQUARE_SIDE?*?ROWS

SCREEN_OFFSET?=?20
SCREEN_SIZE?=?（ROWS?*?（SQUARE_SIDE）?+?2?*?SCREEN_OFFSET?COLUMNS?*?（SQUARE_SIDE）?+?2?*?SCREEN_OFFSET）

#?COLORS
green?=?0?255?0
red?=?255?0?0
blue?=?0?0?255
white?=?255?255?255

#?2?obstacles
#?0?free
#?1?free?cleaned
grid?=?np.zeros（[ROWS?COLUMNS]）

#?OBSTACLES

#?Fig.?5
‘‘‘
grid[4][5]?=?2
grid[4][6]?=?2
grid[4][7]?=?2
grid[4][8]?=?2
grid[4][9]?=?2
grid[4][10]?=?2
grid[4][11]?=?2
grid[4][12]?=?2
grid[4][13]?=?2
grid[4][14]?=?2
grid[4][15]?=?2
grid[4][16]?=?2
grid[4][17]?=?2
grid[4][18]?=?2
grid[4][19]?=?2
‘‘‘
grid[4][5]?=?2
grid[4][6]?=?2

grid_shape?=?grid.shape

print
“?grid?shape?“?+?str（grid.shape）

#?print?len（grid）?#?n?=?5
#?print?len（grid[0]）?#?m?=?6
#?print?grid[1][0]

#?TODO:?initial?point?heading
#

initial?=?[0?0]
init?=?[0?0]
goal?=?[len（grid）?-?1?len（grid[0]）?-?1]
cost?=?1

delta?=?[[-1?0]??#?go?up
?????????[0?-1]??#?go?left
?????????[1?0]??#?go?down
?????????[0?1]]??#?go?right

backtracking_list?=?[]


class?Node:

????def?__init__（self?column?row?cost?pind）:
????????self.column?=?column
????????self.row?=?row
????????self.cost?=?cost
????????self.pind?=?pind??#?parent?indice

????def?__str__（self）:
????????return?str（self.x）?+?““?+?str（self.y）?+?““?+?str（self.cost）?+?““?+?str（self.pind）


#?def?path（grid?initial_point）:

def?verify（direction?row?column）:
????if?direction?==?‘north‘:
????????if?row?<=?0:
????????????return?False
????????elif?grid[row?-?1][column]?==?1?or?grid[row?-?1][column]?==?2:
????????????return?False
????????else:
????????????return?True

????elif?direction?==?‘south‘:

????????if?row?>=?（grid.shape[0]?-?1）:
????????????return?False
????????elif?grid[row?+?1][column]?==?1?or?grid[row?+?1][column]?==?2:
????????????return?False
????????else:
????????????return?True

????elif?direction?==?‘west‘:

????????if?column?<=?0:
????????????return?False
????????elif?grid[row][column?-?1]?==?1?or?grid[row][column?-?1]?==?2:
????????????return?False
????????else:
????????????return?True

????elif?direction?==?‘east‘:

????????if?column?>=?（grid.shape[1]?-?1）:
????????????return?False
????????elif?grid[row][column?+?1]?==?1?or?grid[row][column?+?1]?==?2:
????????????return?False
????????else:
????????????return?True


def?valid_cell（grid?row?column）:
????“““?Verify?is?the?cell?is?valid.?“““
????if?（row?=?0）?and?（column?=?0）:
????????return?True
????else:
????????return?False


def?backtracking_points（grid?row?