Permalink
Find file
Fetching contributors…
Cannot retrieve contributors at this time
83 lines (64 sloc) 2.07 KB
# -----------
# User Instructions:
#
# Modify the function search() so that it returns
# a table of values called expand. This table
# will keep track of which step each node was
# expanded.
#
# For grading purposes, please leave the return
# statement at the bottom.
# ----------
grid = [[0, 0, 1, 0, 0, 0],
[0, 0, 0, 0, 0, 0],
[0, 0, 1, 0, 1, 0],
[0, 0, 1, 0, 1, 0],
[0, 0, 1, 0, 1, 0]]
init = [0, 0]
goal = [len(grid)-1, len(grid[0])-1]
delta = [[-1, 0 ], # go up
[ 0, -1], # go left
[ 1, 0 ], # go down
[ 0, 1 ]] # go right
delta_name = ['^', '<', 'v', '>']
cost = 1
# ----------------------------------------
# modify code below
# ----------------------------------------
def search():
count = 0
closed = [[0 for row in range(len(grid[0]))] for col in range(len(grid))]
closed[init[0]][init[1]] = 1
expand = [[-1 for row in range(len(grid[0]))] for col in range(len(grid))]
expand[init[0]][init[1]] = 0
x = init[0]
y = init[1]
g = 0
open = [[g, x, y]]
found = False # flag that is set when search is complete
resign = False # flag set if we can't find expand
while not found and not resign:
if len(open) == 0:
resign = True
else:
open.sort()
open.reverse()
next = open.pop()
x = next[1]
y = next[2]
g = next[0]
if x == goal[0] and y == goal[1]:
found = True
else:
count += 1
for i in range(len(delta)):
x2 = x + delta[i][0]
y2 = y + delta[i][1]
if x2 >= 0 and x2 < len(grid) and y2 >=0 and y2 < len(grid[0]):
if closed[x2][y2] == 0 and grid[x2][y2] == 0:
g2 = g + cost
open.append([g2, x2, y2])
closed[x2][y2] = 1
expand[x2][y2] = count
return expand #Leave this line for grading purposes!
print search()