advent_of_code_2022

commit 3afc67b9cb99a79240f14d4247eed371dbf47025
parent 2d2c3b50224a67ec8b52aa871246c7672fd7c088
Author: Eamon Caddigan <eamon.caddigan@gmail.com>
Date:   Thu, 15 Dec 2022 20:46:45 -0800

Solution to day 12, part 1.

Finally. I misunderstood the constraints, lol.

Diffstat:
M
src/day_12.jl
 | 
22
+++++++++++++++-------

1 file changed, 15 insertions(+), 7 deletions(-)
diff --git a/src/day_12.jl b/src/day_12.jl
@@ -32,17 +32,25 @@ end
 
 function makegraph(heightmap::AbstractMatrix)
     height, width = size(heightmap)
-    g = Graph(height*width)
+    g = DiGraph(height*width)
     # I wanted to do this elegantly, but meh, just going to brute-force
     # indexing.
     for (i, ind) = enumerate(CartesianIndices(heightmap))
-        if ind[1] < height && 
-                abs(heightmap[ind] - heightmap[ind[1]+1, ind[2]]) <= 1
-            add_edge!(g, i, i+1)
+        if ind[1] < height
+            if heightmap[ind] + 1 >= heightmap[ind[1]+1, ind[2]]
+                add_edge!(g, i, i+1)
+            end
+            if heightmap[ind[1]+1, ind[2]] + 1 >= heightmap[ind]
+                add_edge!(g, i+1, i)
+            end
         end
-        if ind[2] < width && 
-                abs(heightmap[ind] - heightmap[ind[1], ind[2]+1]) <= 1
-            add_edge!(g, i, i+height)
+        if ind[2] < width
+            if heightmap[ind] + 1 >= heightmap[ind[1], ind[2]+1]
+                add_edge!(g, i, i+height)
+            end
+            if heightmap[ind[1], ind[2]+1] + 1 >= heightmap[ind]
+                add_edge!(g, i+height, i)
+            end
         end
     end
     g