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diff --git a/2024/aoc2024-d18.py b/2024/aoc2024-d18.py
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+#advent of code 2024
+#day 18
+#advent of gridbroot
+
+import heapq
+
+mygrid = {};
+FallingBytes = [];
+lim = 70 + 1;
+bytelim = 1024;
+for p in [(X,Y) for Y in range(lim) for X in range(lim)]: mygrid[p] = ".";
+#myfile = "18.ex";
+myfile = "18.in";
+if myfile != "18.in": #if example
+	lim = 7;
+	bytelim = 12;
+
+f = open(myfile,"r");
+for counter,l in enumerate(f):
+	bytex,bytey = [int(v) for v in l.strip().split(",")];
+	FallingBytes.append((bytex,bytey));
+	if counter < bytelim: mygrid[(bytex,bytey)] = "#";
+f.close();
+
+start = (0,0); 
+end = (lim-1,lim-1);
+dirs = [(1,0),(0,1),(-1,0),(0,-1)]; #east, south, west, north
+
+def getAdjacent(grid,coordinates):
+	adj = [];
+	xp, yp = coordinates;
+	for i,d in enumerate(dirs):
+		dx,dy = d;
+		if grid.get((xp+dx,yp+dy),"#") != "#":
+			adj.append((xp+dx,yp+dy));
+	return adj;
+
+def shortestpath(grid,startpos):
+	score = 0;
+	visited = set();
+	queue = [(0,startpos)];
+	while queue:
+		dist, pos = heapq.heappop(queue);
+		if pos in visited: continue;
+		visited.add(pos);
+		if pos == end:
+			score = dist;
+			break;
+		NextPositions = getAdjacent(grid,pos);
+		for NP in NextPositions:
+			heapq.heappush(queue,(dist+1,NP));
+	return score
+
+part1 = shortestpath(mygrid,start);
+print("part 1 =",part1);
+part2 = None;
+for b_ind,b in enumerate(FallingBytes[bytelim:]):
+	mygrid[b] = "#";
+	path = shortestpath(mygrid,start);
+	if path == 0: 
+		part2 = f'{b[0]},{b[1]}';
+		break;
+
+print("part 2 =",part2);