day 16 task 1 and not working idea of task 2...

src/tasks/day16.rs

@@ -0,0 +1,77 @@
+use itertools::Itertools;
+use num_integer::Integer;
+use std::iter;
+
+#[allow(dead_code)]
+pub fn run() {
+    let input = "03036732577212944063491565474664" //"59750530221324194853012320069589312027523989854830232144164799228029162830477472078089790749906142587998642764059439173975199276254972017316624772614925079238407309384923979338502430726930592959991878698412537971672558832588540600963437409230550897544434635267172603132396722812334366528344715912756154006039512272491073906389218927420387151599044435060075148142946789007756800733869891008058075303490106699737554949348715600795187032293436328810969288892220127730287766004467730818489269295982526297430971411865028098708555709525646237713045259603175397623654950719275982134690893685598734136409536436003548128411943963263336042840301380655801969822"
+        .chars()
+        .map(|it| it.to_digit(10).unwrap() as i32)
+        .collect_vec();
+    task1(input.clone());
+    task2(input.clone());
+}
+
+fn task1(input: Vec<i32>) {
+    let p = [0, 1, 0, -1];
+    let result = (0..100).fold(input, |old, _| {
+        (1..=old.len())
+            .map(|position| {
+                let pattern = p
+                    .iter()
+                    .map(|x| std::iter::repeat(*x).take(position))
+                    .flatten();
+                let val: i32 = old
+                    .iter()
+                    .zip(std::iter::repeat(pattern).flatten().skip(1))
+                    .map(|(value, multiplier)| value * multiplier)
+                    .sum();
+                val.abs() % 10
+            })
+            .collect_vec()
+    });
+    println!("Task 1: {:.*}", 8, result.iter().join(""));
+}
+
+fn task2(input: Vec<i32>) {
+    let l = input.len() * 10_000;
+    let big_input = iter::repeat(input.clone().into_iter())
+        .flatten()
+        .take(l)
+        .collect_vec();
+    let p = [0, 1, 0, -1];
+    let result = (0..100).fold(big_input, |old, _| {
+        (1..=old.len())
+            .map(|position| {
+                let pattern = p.iter().map(|x| iter::repeat(*x).take(position)).flatten();
+                let iter = iter::repeat(pattern).flatten().skip(1);
+                let repeats_after = (4 * position).lcm(&input.len());
+                if repeats_after > l {
+                    l
+                } else {
+                    repeats_after
+                };
+                let part: i32 = iter::repeat(input.iter())
+                    .flatten()
+                    .zip(iter.clone())
+                    .take(repeats_after)
+                    .map(|(value, multiplier)| value * multiplier)
+                    .sum();
+                let part_fits = l / repeats_after;
+                let most_parts = part * part_fits as i32;
+
+                let number_rest = l / repeats_after;
+                let part_rest: i32 = iter
+                    .zip(iter::repeat(input.iter()).flatten())
+                    .take(number_rest)
+                    .map(|(value, multiplier)| value * multiplier)
+                    .sum();
+
+                (part_rest + most_parts) % 10
+            })
+            .collect_vec()
+    });
+    let offset = input[0..7].iter().join("").parse::<usize>().unwrap();
+    let message = result[offset..offset + 8].iter().join("");
+    println!("Task 2: {}", message);
+}