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adventofcode2023
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day 17 fix cost calculation 

i was accidentally using the previous coordinates to calculate the cost
for each node, which means the A* search was effectively calculating the
cost of the return trip instead of the forward path.
doesn't affect the path at all - the start and end nodes are fixed, so
it doesn't matter whether their costs are included or not - but it does
mean that the cost being returned at the end was off by ((value at end
point) - (value at start point)) compared to the expected value.
main
magical 2023-12-17 06:42:34 +00:00
parent 14ef33326e
commit fe76e83e98
1 changed files with 3 additions and 6 deletions
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9
day17/sol.py
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@ -10,7 +10,7 @@ def solve(map,part=1):
start = (0,0,(0,0),0) start = (0,0,(0,0),0)
goal = (len(map)-1,len(map[-1])-1) goal = (len(map)-1,len(map[-1])-1)
def is_goal(x): def is_goal(x):
return (x[1],x[0]) == goal return x[:2] == goal
def neighbors(state): def neighbors(state):
y,x,dir,count = state y,x,dir,count = state
next = [] next = []
@ -33,7 +33,7 @@ def solve(map,part=1):
if newcount <= count < 4: if newcount <= count < 4:
return return
if (0 <= newy < len(map)) and (0 <= newx < len(map[newy])): if (0 <= newy < len(map)) and (0 <= newx < len(map[newy])):
next.append((map[y][x], (newy, newx, (dx,dy), newcount))) next.append((map[newy][newx], (newy, newx, (dx,dy), newcount)))
go(-1,0) go(-1,0)
go(+1,0) go(+1,0)
go(0,-1) go(0,-1)
@ -41,12 +41,9 @@ def solve(map,part=1):
return next return next
cost, node, path = astar.search(start, is_goal, neighbors) cost, node, path = astar.search(start, is_goal, neighbors)
print(cost) # TODO: off by one somehow? print(cost)
print([(x,y) for (y,x,_,_) in path]) print([(x,y) for (y,x,_,_) in path])
print(''.join(dir2s(d) for (_,_,d,_) in path)) print(''.join(dir2s(d) for (_,_,d,_) in path))
costs = [map[y][x] for (y,x,_,_) in path[1:]]
print(costs)
print(sum(costs))
def dir2s(d): def dir2s(d):
if d == (0,1): return "v" if d == (0,1): return "v"