Added day 20

src/day20/1.rs

@@ -0,0 +1,63 @@
+#![feature(test)]
+extern crate test;
+
+const INPUTS: [&[u8]; 2] = [
+    include_bytes!("./sample.txt"),
+    include_bytes!("./input.txt"),
+];
+
+fn parse(input: &[u8]) -> Vec<i32> {
+    input
+        .split(|&b| b == b'\n')
+        .filter(|c| !c.is_empty())
+        .map(|line| {
+            let isneg = line.starts_with(&[b'-']);
+
+            let num = line
+                .iter()
+                .filter(|c| (b'0'..=b'9').contains(c))
+                .fold(0, |a, x| (a * 10) + (x - b'0') as i32);
+            if isneg {
+                -num
+            } else {
+                num
+            }
+        })
+        .collect()
+}
+
+fn solution(input: Vec<i32>) -> i32 {
+    let l = input.len() as i32;
+
+    let mut idxes = (0..l as usize).collect::<Vec<usize>>();
+
+    for (i, num) in input.iter().enumerate() {
+        let pos = idxes.iter().position(|&c| c == i).unwrap();
+        idxes.remove(pos);
+        let new_idx = (pos as i32 + num).rem_euclid(idxes.len() as i32) as usize;
+        idxes.insert(new_idx, i);
+    }
+
+    let orig_zero_i = input.iter().position(|&i| i == 0).unwrap();
+    let zero_i = idxes.iter().position(|&i| i == orig_zero_i).unwrap();
+    [1000, 2000, 3000]
+        .iter()
+        .map(|i| input[idxes[(zero_i + i) % idxes.len()]])
+        .sum()
+}
+
+fn main() {
+    for input in INPUTS.iter() {
+        let output = parse(input);
+        let score = solution(output);
+        println!("{}", score);
+    }
+}
+#[bench]
+fn solution_bench(b: &mut test::Bencher) {
+    b.iter(|| {
+        let input = parse(INPUTS[1]);
+        let result = solution(input);
+        test::black_box(result);
+    })
+}

src/day20/2.rs

@@ -0,0 +1,65 @@
+#![feature(test)]
+extern crate test;
+
+const INPUTS: [&[u8]; 2] = [
+    include_bytes!("./sample.txt"),
+    include_bytes!("./input.txt"),
+];
+
+fn parse(input: &[u8]) -> Vec<i64> {
+    input
+        .split(|&b| b == b'\n')
+        .filter(|c| !c.is_empty())
+        .map(|line| {
+            let isneg = line.starts_with(&[b'-']);
+
+            let num = line
+                .iter()
+                .filter(|c| (b'0'..=b'9').contains(c))
+                .fold(0, |a, x| (a * 10) + (x - b'0') as i64);
+            if isneg {
+                -num * 811589153
+            } else {
+                num * 811589153
+            }
+        })
+        .collect()
+}
+
+fn solution(input: Vec<i64>) -> i64 {
+    let l = input.len() as i64;
+
+    let mut idxes = (0..l as usize).collect::<Vec<usize>>();
+
+    for _ in 0..10 {
+        for (i, num) in input.iter().enumerate() {
+            let pos = idxes.iter().position(|&c| c == i).unwrap();
+            idxes.remove(pos);
+            let new_idx = (pos as i64 + num).rem_euclid(idxes.len() as i64) as usize;
+            idxes.insert(new_idx, i);
+        }
+    }
+
+    let orig_zero_i = input.iter().position(|&i| i == 0).unwrap();
+    let zero_i = idxes.iter().position(|&i| i == orig_zero_i).unwrap();
+    [1000, 2000, 3000]
+        .iter()
+        .map(|i| input[idxes[(zero_i + i) % idxes.len()]])
+        .sum()
+}
+
+fn main() {
+    for input in INPUTS.iter() {
+        let output = parse(input);
+        let score = solution(output);
+        println!("{}", score);
+    }
+}
+#[bench]
+fn solution_bench(b: &mut test::Bencher) {
+    b.iter(|| {
+        let input = parse(INPUTS[1]);
+        let result = solution(input);
+        test::black_box(result);
+    })
+}

src/day20/sample.txt

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