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#advent of code 2018
#day 20
#part 1 and part 2
#I struggled with indexing when parsing the input
#I was getting more doors mapped than there really were
#the issue was that after parsing the content of a bracket
#I was retreiving a ")" sign instead of the following instruction like N or W
#+1 to the index did the work
#a bit disappointed with part 2, on which I spent more time reading it than coding
f = open("input.txt",'r');
Testing = False;
#Testing = True;
if Testing:
f.close();
f = open("testinput.txt",'r');
inputline = f.readline();
inputline = inputline[1:-1];
f.close();
#split the contents of a bracket into separate strings, return a list of those strings
def parse_brackets(regex):
regex = regex[1:];
close_brackets_sign = ")";
close_brackets_count = 1;
subsets = [];
subset = "";
for i, c in enumerate(regex):
if c == "(":
close_brackets_count += 1;
subset += c;
elif c == close_brackets_sign:
if close_brackets_count == 1:
subsets.append(subset);
break;
else:
close_brackets_count -= 1;
subset += c;
elif c == "|":
if close_brackets_count == 1:
subsets.append(subset);
subset = "";
else: subset += c;
else: subset += c;
return i, subsets;
#fill up the "area" dictionary with rooms and doors based on provided instruction
#recursive function, the function is called again if the path is branching due to brackets
def parse_input(inputline, Cords, grid):
i = 0;
d = (0,0);
CurrentCords = Cords;
CurrentCords = (CurrentCords[0] +d[0],CurrentCords[1] +d[1]);
while i < len(inputline):
c = inputline[i];
if c == "(":
x, subs = parse_brackets(inputline[i:]);
for s in subs:
parse_input(s, CurrentCords, grid);
i += x+1;
elif c == "$":
break;
else:
if c == "N":
d = (0,-1);
elif c == "S":
d = (0,1);
elif c == "W":
d = (-1,0);
elif c == "E":
d = (1,0);
CurrentCords = (CurrentCords[0] +d[0],CurrentCords[1] +d[1]);
grid.update({CurrentCords:"D"});
CurrentCords = (CurrentCords[0] +d[0],CurrentCords[1] +d[1]);
grid.update({CurrentCords:"."});
i += 1;
area = {};
p = (0,0);
area.update({p:"."});
parse_input(inputline, p, area);
#print the map of the area
'''
maxX = max([x[0] for x in area]);
minX = min([x[0] for x in area]);
maxY = max([y[1] for y in area]);
minY = min([y[1] for y in area]);
for y in range(minY-1, maxY+1+1):
for x in range(minX-1, maxX+1+1):
cp = area.get((x,y),"#");
if x==0 and y==0: cp = "X";
print(cp, end="");
print();
'''
distances = {};
queue = [(0,0,0)];
while queue:
x,y,d = queue.pop();
if ((x,y) in distances and distances.get((x,y)) <= d):
continue;
distances.update({(x,y):d});
if (x+1,y) in area and (x+2,y) in area: queue.append((x+2,y,d+1));
if (x-1,y) in area and (x-2,y) in area: queue.append((x-2,y,d+1));
if (x,y+1) in area and (x,y+2) in area: queue.append((x,y+2,d+1));
if (x,y-1) in area and (x,y-2) in area: queue.append((x,y-2,d+1));
part1 = max([distances[dist] for dist in distances]);
print("part1 = ", part1);
part2 =len([distances[dist] for dist in distances if distances[dist]>=1000]);
print("part2 = ", part2);
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