Started with aoc 2015, unable to make d4 part2 faster. Multi-threaded actually slower

y2015/src/bin/d1.rs

@@ -0,0 +1,20 @@
+use std::fs;
+
+use y2015::days::d1;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/1_input.txt")).unwrap();
+    println!("{}", d1::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/1_input.txt")).unwrap();
+    println!("{}", d1::process_part2(&content));
+}

y2015/src/bin/d2.rs

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+use std::fs;
+
+use y2015::days::d2;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/2_input.txt")).unwrap();
+    println!("{}", d2::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/2_input.txt")).unwrap();
+    println!("{}", d2::process_part2(&content));
+}

y2015/src/bin/d3.rs

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+use std::fs;
+
+use y2015::days::d3;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/3_input.txt")).unwrap();
+    println!("{}", d3::process_part1(&content));
+}
+
+fn part2() {
+    let root = env!("CARGO_MANIFEST_DIR");
+    let content = fs::read_to_string(format!("{root}/resources/3_input.txt")).unwrap();
+    println!("{}", d3::process_part2(&content));
+}

y2015/src/bin/d4.rs

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+use std::time::Instant;
+
+use y2015::days::d4;
+
+fn main() {
+    part1();
+    part2();
+}
+
+fn part1() {
+    let now = Instant::now();
+    println!("{}", d4::process_part1("bgvyzdsv"));
+    println!("{}µs", now.elapsed().as_micros());
+}
+
+fn part2() {
+    let now = Instant::now();
+    println!("{}", d4::process_part2("bgvyzdsv"));
+    println!("{}µs", now.elapsed().as_micros());
+}