From 01197254cc1283ecdd44eac84975925919afd235 Mon Sep 17 00:00:00 2001
From: Jesse Luehrs <doy@tozt.net>
Date: Thu, 23 Dec 2021 03:39:41 -0500
Subject: day 23

---
 examples/2021_23_generate_connectivity.rs | 122 ++++++++++++++++++++++++++++++
 1 file changed, 122 insertions(+)
 create mode 100644 examples/2021_23_generate_connectivity.rs

(limited to 'examples')

diff --git a/examples/2021_23_generate_connectivity.rs b/examples/2021_23_generate_connectivity.rs
new file mode 100644
index 0000000..6f02da6
--- /dev/null
+++ b/examples/2021_23_generate_connectivity.rs
@@ -0,0 +1,122 @@
+// #############
+// #abcdefghijk#
+// ###l#m#n#o###
+//   #p#q#r#s#
+//   #########
+static NEIGHBORS1: &[&[usize]] = &[
+    &[1],
+    &[0, 2],
+    &[1, 3, 11],
+    &[2, 4],
+    &[3, 5, 12],
+    &[4, 6],
+    &[5, 7, 13],
+    &[6, 8],
+    &[7, 9, 14],
+    &[8, 10],
+    &[9],
+    &[2, 15],
+    &[4, 16],
+    &[6, 17],
+    &[8, 18],
+    &[11],
+    &[12],
+    &[13],
+    &[14],
+];
+
+// #############
+// #abcdefghijk#
+// ###l#m#n#o###
+//   #p#q#r#s#
+//   #t#u#v#w#
+//   #x#y#z#!#
+//   #########
+static NEIGHBORS2: &[&[usize]] = &[
+    &[1],
+    &[0, 2],
+    &[1, 3, 11],
+    &[2, 4],
+    &[3, 5, 12],
+    &[4, 6],
+    &[5, 7, 13],
+    &[6, 8],
+    &[7, 9, 14],
+    &[8, 10],
+    &[9],
+    &[2, 15],
+    &[4, 16],
+    &[6, 17],
+    &[8, 18],
+    &[11, 19],
+    &[12, 20],
+    &[13, 21],
+    &[14, 22],
+    &[15, 23],
+    &[16, 24],
+    &[17, 25],
+    &[18, 26],
+    &[19],
+    &[20],
+    &[21],
+    &[22],
+];
+
+fn path_rec(
+    neighbors: &[&[usize]],
+    from: usize,
+    to: usize,
+    path: &mut Vec<usize>,
+) -> bool {
+    if from == to {
+        return true;
+    }
+    for neighbor in neighbors[from] {
+        if path.contains(neighbor) {
+            continue;
+        }
+        path.push(*neighbor);
+        if path_rec(neighbors, *neighbor, to, path) {
+            return true;
+        }
+        path.pop();
+    }
+    false
+}
+
+fn path(neighbors: &[&[usize]], from: usize, to: usize) -> Vec<usize> {
+    let mut path = vec![from];
+    if !path_rec(neighbors, from, to, &mut path) {
+        panic!("no path found from {} to {}", from, to);
+    }
+    path.remove(0);
+    path
+}
+
+fn main() {
+    println!("static CONNECTIVITY1: &[&[&[usize]]] = &[");
+    for from in 0..19 {
+        println!("    &[");
+        for to in 0..19 {
+            let path = path(NEIGHBORS1, from, to);
+            let path_strs: Vec<_> =
+                path.iter().map(|i| i.to_string()).collect();
+            println!("        &[{}],", path_strs.join(", "));
+        }
+        println!("    ],");
+    }
+    println!("];");
+    println!();
+    println!("static CONNECTIVITY2: &[&[&[usize]]] = &[");
+    for from in 0..27 {
+        println!("    &[");
+        for to in 0..27 {
+            let path = path(NEIGHBORS2, from, to);
+            let path_strs: Vec<_> =
+                path.iter().map(|i| i.to_string()).collect();
+            println!("        &[{}],", path_strs.join(", "));
+        }
+        println!("    ],");
+    }
+    println!("];");
+}
-- 
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