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# coding: utf-8
import os, sys
from z3 import *
# get the playground information
if len(sys.argv) != 2:
print("Usage: python3 trees_and_tents.py <forest-file>")
EMPTY = "?"
TREE = 2
if len(sys.argv) == 2:
fname = sys.argv[1]
with open(fname) as f:
playground = f.read()
cols = [col for col in playground.strip().split("\n")[0][1:]]
rows = [row[0] for row in playground.strip().split("\n")[1:]]
playground = [[EMPTY if x == EMPTY else x for x in row[1:]]
for row in playground.strip().split("\n")[1:]]
# get the playground size
len_rows = len(rows)
assert(len_rows != 0)
len_cols = len(cols)
assert(len_cols != 0)
def print_result(model):
print(" " + ''.join(cols) + " "*5 + ''.join(cols))
for i in range(len_rows):
print(rows[i] + " " + ''.join(playground[i]) + " >>> ", end='')
for j in range(len_cols):
cell = model[cells[i][j]].as_long()
if cell != TREE:
print(cell, end='')
elif cell == TREE:
print("T", end='')
print()
def print_forest():
print(" " + ''.join(cols))
for i in range(len_rows):
print(rows[i] + " ", end='')
for j in range(len_cols):
cell = playground[i][j]
if cell != TREE:
print(cell, end='')
elif cell == TREE:
print("T", end='')
print()
################################# Trees and Tents ##################################
# create the solver
solver = Solver()
cells = [[None for j in range(len_cols)] for i in range(len_rows)]
def get_possible_tents_in_col(col):
possible_tent_positions = []
for row in range(len_rows):
if playground[row][col] != "T":
possible_tent_positions.append(cells[row][col])
return possible_tent_positions
def get_possible_tents_in_row(row):
possible_tent_positions = []
for col in range(len_cols):
if playground[row][col] != "T":
possible_tent_positions.append(cells[row][col])
return possible_tent_positions
def get_neighbours(i, j):
cs = []
for p in range(max(i-1, 0), min(i+2, len_rows)):
for q in range(max(j-1, 0), min(j+2, len_cols)):
if p == i and q == j: continue
cs.append(cells[p][q])
return cs
def get_tree_neighbours(i, j):
tree_pos = []
for p in [max(i-1, 0), min(i+1, len_rows - 1)]:
if p == i: continue
tree_pos.append(cells[p][j])
for q in [max(j-1, 0), min(j+1, len_cols - 1)]:
if q == j: continue
tree_pos.append(cells[i][q])
return tree_pos
# TODO
# Cell entries need to be represented by a Z3 variable
for i in range(len_rows):
for j in range(len_cols):
# your code goes here...
# TODO
# Bound/restrict the values of the cells according to the input
if playground[i][j] == EMPTY:
# your code goes here...
else:
# your code goes here...
# TODO
# The sums of tents per row/column must match the amounts given in the input
for j in range(len_cols):
# your code goes here...
for i in range(len_rows):
# your code goes here...
for i in range(len_rows):
for j in range(len_cols):
if playground[i][j] == "T": continue
tree_constraint = Bool("False")
# TODO
# A tent needs to be next to a tree
# Incrementally build up the tree_constraint ...
for possible_tree in get_tree_neighbours(i, j):
# your code goes here...
# ... and add it to the solver
# TODO
# A tent must not be next to another tent
for neighbour in get_neighbours(i, j):
# your code goes here...
res = solver.check()
if res == unsat:
print("UNSAT")
print_forest()
else:
m = solver.model()
print_result(m)