Add tailcall-notes to Day 6

Author: ochsnerd

Cargo.lock

@@ -8,4 +8,5 @@ edition = "2021"
 [dependencies]
 clap = { version = "4.4", features = ["derive"] }
 itertools = "0.14.0"
-rayon = "1.8"
+rayon = "1.8"
+tailcall = "1.0.1"

Cargo.toml

@@ -6,6 +6,7 @@
 // - the 'functional' setup allows of trivial parallelization
 
 use itertools::Itertools;
+use tailcall::tailcall;
 use rayon::prelude::*;
 use std::collections::BTreeMap;
 use std::collections::HashMap;
@@ -391,6 +392,10 @@ impl Lines {
     }
 }
 
+// see https://stackoverflow.com/q/59257543 etc
+// also check out what happens if the recursive call is replaced with
+// would_loop(...) == true
+#[tailcall]
 // Would this setup result in a loop?
 fn would_loop(
     guard: Guard,

src/day06.rs

@@ -24,7 +24,7 @@ fn main() {
 	3 => day03::day03(input),
 	4 => day04::day04(input),
 	5 => day05::day05(input),
-	6 => day06::day06(input),
-	_ => day07::day07(input),
+	7 => day07::day07(input),
+	_ => day06::day06(input),
     }
 }