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Diffstat (limited to 'racket/aoc2023/day-25/day-25.rkt')
-rw-r--r-- | racket/aoc2023/day-25/day-25.rkt | 43 |
1 files changed, 43 insertions, 0 deletions
diff --git a/racket/aoc2023/day-25/day-25.rkt b/racket/aoc2023/day-25/day-25.rkt new file mode 100644 index 0000000..aa32e43 --- /dev/null +++ b/racket/aoc2023/day-25/day-25.rkt @@ -0,0 +1,43 @@ +#lang racket + +(require advent-of-code + threading + graph) + +(define input + (~> (fetch-aoc-input (find-session) 2023 25 #:cache #true) + (string-split "\n") + (map (curryr string-split ": ") _))) + +(define all-wires + (for*/list ([wire-diagram (in-list input)] [devices (in-list (string-split (second wire-diagram)))]) + (list (car wire-diagram) devices))) + +;; instead of trying to solve the minimum cut problem, I generated the graph and +;; rendered it in graphviz: + +; (define out (open-output-file "graphviz")) +; (~> all-wires +; unweighted-graph/undirected +; graphviz +; (display out)) +; (close-output-port out) + +;; the bottleneck is very obvious on the graph -- +;; there's two large clusters of nodes, connected by just three edges +;; +;; from the graphviz output, the three critical wires are +;; cpq-hlx +;; hqp-spk +;; chr-zlx + +(define remove-these-three '(("cpq" "hlx") ("hqp" "spk") ("chr" "zlx"))) +(define cut-wires + (for/list ([wire (in-list all-wires)] #:unless (member (sort wire string<?) remove-these-three)) + wire)) + +(~> cut-wires + unweighted-graph/undirected + scc + (map length _) + (apply * _))
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