day 23 puzzle 2

progress.yaml

@@ -41,4 +41,6 @@
 21:
   stars: 0
 22:
-  stars: 1
+  stars: 1
+23:
+  stars: 2

res/examples/day23.txt

@@ -0,0 +1,32 @@
+kh-tc
+qp-kh
+de-cg
+ka-co
+yn-aq
+qp-ub
+cg-tb
+vc-aq
+tb-ka
+wh-tc
+yn-cg
+kh-ub
+ta-co
+de-co
+tc-td
+tb-wq
+wh-td
+ta-ka
+td-qp
+aq-cg
+wq-ub
+ub-vc
+de-ta
+wq-aq
+wq-vc
+wh-yn
+ka-de
+kh-ta
+co-tc
+wh-qp
+tb-vc
+td-yn

src/day23/puzzle1.typ

@@ -0,0 +1,50 @@
+#import "/src/utils.typ": *
+
+#let solve(input) = {
+  let links = input.split("\n")
+
+  let links-dict = (:)
+
+  let to-test = ()
+  for link in links {
+    let (a, b) = link.split("-")
+    if a not in links-dict {
+      links-dict.insert(a, ())
+    }
+    if b not in links-dict {
+      links-dict.insert(b, ())
+    }
+    links-dict.at(a).push(b)
+    links-dict.at(b).push(a)
+    if a.starts-with("t") {
+      to-test.push(a)
+    }
+    if b.starts-with("t") {
+      to-test.push(b)
+    }
+  }
+
+  let total = 0
+  let groups = ()
+  for comp1 in to-test.dedup() {
+    for comp2 in links-dict.at(comp1) {
+      for comp3 in links-dict.at(comp2) {
+        if comp1 in links-dict.at(comp3) {
+          let group = (comp1, comp2, comp3).sorted()
+          if group not in groups {
+            total += 1
+            groups.push(group)
+          }
+        }
+      }
+    }
+  }
+
+  return total
+}
+
+#show-puzzle(
+  23, 1,
+  solve,
+  example: 7
+)

src/day23/puzzle2.typ

@@ -0,0 +1,65 @@
+#import "/src/utils.typ": *
+
+#let bron-kerbosch(links, R, P, X) = {
+  if P.len() == 0 and X.len() == 0 {
+    return if R.len() > 2 {
+      R.sorted()
+    } else {
+      none
+    }
+  }
+
+  let longest-len = 0
+  let longest = none
+  let to-visit = P
+  for v in to-visit {
+    let neighbors = links.at(v)
+    let clique = bron-kerbosch(
+      links,
+      R + (v,),
+      P.filter(n => n in neighbors),
+      X.filter(n => n in neighbors)
+    )
+    if clique != none {
+      let l = clique.len()
+      if longest == none or l > longest-len {
+        longest = clique
+        longest-len = l
+      }
+    }
+    let _ = P.remove(0)
+    X.push(v)
+  }
+  return longest
+}
+
+#let solve(input) = {
+  let links = input.split("\n")
+
+  let links-dict = (:)
+
+  let to-test = ()
+  for link in links {
+    let (a, b) = link.split("-")
+    if a not in links-dict {
+      links-dict.insert(a, ())
+    }
+    if b not in links-dict {
+      links-dict.insert(b, ())
+    }
+    links-dict.at(a).push(b)
+    links-dict.at(b).push(a)
+  }
+
+  let clique = bron-kerbosch(links-dict, (), links-dict.keys(), ())
+
+  return clique.join(",")
+}
+
+#show-puzzle(
+  23, 2,
+  solve,
+  example: "co,de,ka,ta",
+  only-example: true
+)
+#show-result("ab,al,cq,cr,da,db,dr,fw,ly,mn,od,py,uh")