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#advent of code 2024
#day 14
#correctly assumed that the picture will show up
#if the robots don't overlap
#doing previous years with online help paid off
#NOTE: I learned that it's not recommended to
#take modulo of a negative value
#however there was no problem with that in python
import re
class robot:
def __init__(self,rx,ry,rvx,rvy):
self.posx = rx;
self.posy = ry;
self.startx = rx; #useless, no need to reset
self.starty = ry; #useless, no need to reset
self.velx = rvx;
self.vely = rvy;
def move(self,steps):
self.posx = (self.posx + steps*self.velx)%xMax;
self.posy = (self.posy + steps*self.vely)%yMax;
def currentpos(self):
return (self.posx,self.posy);
def resetpos(self): #useless, no need to reset
self.posx = self.startx;
self.posy = self.starty;
robots = [];
xMin = 0; #from part 1 description, grid range
yMin = 0; #from part 1 description, grid range
xMax = 101; #from part 1 description, grid range
yMax = 103; #from part 1 description, grid range
f = open("14.in","r");
for l in f:
nums = re.findall(r'-?\d+',l)
robots.append(robot(*[int(n) for n in nums]));
f.close();
RobotPositions = {};
TimeElapsed = 100; #from part 1 description, time of simulation
for r in robots:
r.move(TimeElapsed);
robx,roby = r.currentpos();
if RobotPositions.get((robx,roby),None) == None:
RobotPositions[(robx,roby)] = 0;
RobotPositions[(robx,roby)] += 1;
part1 = 1; #Safety Factor to multiply
qlim = [(0,xMax//2,0,yMax//2),(1+xMax//2,xMax+1,0,yMax//2),(0,xMax//2,1+yMax//2,yMax+1),(1+xMax//2,xMax+1,1+yMax//2,yMax+1)];
#qlim = ranges of each quadrant in format: x_min,x_max,y_min,y_max
#not to be confused with xMin,xMax,yMin,yMax of the total grid
#could probably change it a bit and check which quadrant given robot
#belongs to after calculating its position at TimeElapsed
#and count them during "r in robots" for loop
for qx1,qx2,qy1,qy2 in qlim:
robotcountq = 0; #number of robots for each quadrant
for y in range(qy1,qy2):
for x in range(qx1,qx2):
robotcountq += RobotPositions.get((x,y),0);
part1 *= robotcountq;
print("part 1 = ", part1);
TotalRobots = len(robots);
#I assume (in hindsight: correctly) that the picture doesn't show up before the 100s mark from part 1
#in general robots' positions should be reset and then start the timer from t = 0
while True:
TimeElapsed += 1;
RobotSpots = set();
for r in robots:
r.move(1);
robx,roby = r.currentpos();
RobotSpots.add((robx,roby));
if len(RobotSpots)==TotalRobots: break;
part2 = TimeElapsed;
print("part 2 = ", part2);
#commented out the print of the tree itself
#for y in range(yMax):
# for x in range(xMax):
# c = ".";
# if (x,y) in RobotSpots: c = "#";
# #c = RobotPositions.get((x,y),".");
# print(c,end="");
# print();
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