do day 20

2022/input/day_20_sample.txt

@@ -0,0 +1,7 @@
+1
+2
+-3
+3
+-2
+0
+4

2022/src/day_20.rs

@@ -0,0 +1,80 @@
+type Data = Vec<i64>;
+type Output = i64;
+fn parse(input: &str) -> Data {
+    input.lines().map(|s| s.parse().unwrap()).collect()
+}
+fn part_one(data: Data) -> Output {
+    let mut data: Vec<(usize, i64)> = data.into_iter().enumerate().collect();
+    let start_order = data.clone();
+    for (start_idx, num) in start_order.into_iter().filter(|(_, num)| *num != 0) {
+        let idx = data
+            .iter()
+            .enumerate()
+            .find(|(_, (idx, _))| start_idx == *idx)
+            .map(|(idx, _)| idx as i64)
+            .unwrap();
+
+        data.remove(idx as usize);
+        let len = data.len() as Output;
+        let mut new_idx = (idx + num) % len;
+
+        if new_idx <= 0 {
+            new_idx += len;
+        }
+
+        data.insert(new_idx as usize, (start_idx, num));
+    }
+    let zero_idx = data
+        .iter()
+        .enumerate()
+        .find(|(_, (_, num))| *num == 0)
+        .map(|(idx, _)| idx)
+        .unwrap();
+    let get_num = |n: usize| data[(n + zero_idx) % data.len()].1;
+    get_num(1000) + get_num(2000) + get_num(3000)
+}
+fn part_two(data: Data) -> Output {
+    let mut data: Vec<(usize, i64)> = data
+        .into_iter()
+        .map(|num| num * 811589153)
+        .enumerate()
+        .collect();
+    let start_order = data.clone();
+    for _ in 0..10 {
+        for (start_idx, num) in start_order.clone().into_iter().filter(|(_, num)| *num != 0) {
+            let idx = data
+                .iter()
+                .enumerate()
+                .find(|(_, (idx, _))| start_idx == *idx)
+                .map(|(idx, _)| idx as i64)
+                .unwrap();
+
+            data.remove(idx as usize);
+            let len = data.len() as Output;
+            let mut new_idx = (idx + num) % len;
+
+            if new_idx <= 0 {
+                new_idx += len;
+            }
+
+            data.insert(new_idx as usize, (start_idx, num));
+        }
+    }
+    let zero_idx = data
+        .iter()
+        .enumerate()
+        .find(|(_, (_, num))| *num == 0)
+        .map(|(idx, _)| idx)
+        .unwrap();
+    let get_num = |n: usize| data[(n + zero_idx) % data.len()].1;
+    get_num(1000) + get_num(2000) + get_num(3000)
+}
+
+advent_of_code_macro::generate_tests!(
+    day 20,
+    parse,
+    part_one,
+    part_two,
+    sample tests [3, 1_623_178_306],
+    star tests [7_153, 6_146_976_244_822]
+);

2022/src/lib.rs

@@ -18,3 +18,4 @@ mod day_16;
 mod day_17;
 mod day_18;
 mod day_19;
+mod day_20;