Added day23

inputs/day23.txt

@@ -0,0 +1 @@
+963275481

inputs/test.txt

@@ -1,13 +1 @@
-Player 1:
-9
-2
-6
-3
-1
-
-Player 2:
-5
-8
-4
-7
-10
+963275481

src/bin/day23.rs

@@ -0,0 +1,77 @@
+use std::error::Error;
+use std::fs::File;
+use std::io::{self, BufRead};
+use std::vec::Vec;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let file = File::open("inputs/day23.txt")?;
+    let mut lines = io::BufReader::new(file).lines().map(|l| l.unwrap());
+    let line = lines.nth(0).expect("No line in file.");
+
+    let mut cups: Vec<usize> = line
+        .chars()
+        .map(|c| c.to_string().parse().expect("Can't parse number"))
+        .collect();
+
+    let mut cur_pos = 0;
+    for m in 1..101 {
+        println!("Move: {}", m);
+        println!("Cups: {:?}", cups);
+
+        let cur_cup = cups[cur_pos];
+        println!("Current: {}", cur_cup);
+
+        let mut taken = Vec::new();
+
+        for i in 0..3 {
+            let cup = cups[(cur_pos + 1 + i) % cups.len()];
+            taken.push(cup);
+        }
+        println!("Taken: {:?}", taken);
+        cups = cups
+            .iter()
+            .cloned()
+            .filter(|c| !taken.iter().any(|oc| c == oc))
+            .collect();
+
+        let min = cups.iter().fold(cups[0], |a, b| usize::min(a, *b));
+        let max = cups.iter().fold(cups[0], |a, b| usize::max(a, *b));
+
+        let mut dest_cup = cur_cup;
+        loop {
+            dest_cup = if dest_cup < min { max } else { dest_cup - 1 };
+            if let Some(pos) = cups.iter().position(|c| *c == dest_cup) {
+                println!("Dest: {}", dest_cup);
+                for taken_cup in taken.iter().rev() {
+                    cups.insert(pos + 1, *taken_cup);
+                }
+                break;
+            }
+        }
+
+        // Rotate cups to keep the current cup at the same index
+        while cups[cur_pos] != cur_cup {
+            let cup = cups.remove(0);
+            cups.push(cup);
+        }
+
+        cur_pos = (cur_pos + 1) % cups.len();
+        println!("=============================")
+    }
+
+    // Rotate cups make 1 the first
+    while cups[0] != 1 {
+        let cup = cups.remove(0);
+        cups.push(cup);
+    }
+
+    let answer = cups.iter().skip(1).fold(0, |a, c| a * 10 + c);
+    println!("Answer: {}", answer);
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::*;
+}

src/bin/day23_part2.rs

@@ -0,0 +1,75 @@
+use std::error::Error;
+use std::fs::File;
+use std::io::{self, BufRead};
+use std::vec::Vec;
+
+fn main() -> Result<(), Box<dyn Error>> {
+    let file = File::open("inputs/day23.txt")?;
+    let mut lines = io::BufReader::new(file).lines().map(|l| l.unwrap());
+    let line = lines.nth(0).expect("No line in file.");
+
+    let input: Vec<usize> = line
+        .chars()
+        .map(|c| c.to_string().parse().expect("Can't parse number"))
+        .collect();
+
+    let cup_count = 1_000_000;
+
+    // Initilize the linked list with cup_count ordered cups
+    let mut cups = Vec::with_capacity(cup_count + 1);
+    for v in 0..cup_count + 1 {
+        cups.push(v + 1)
+    }
+
+    // Order the first ten according to the input
+    for i in 0..input.len() - 1 {
+        let cup = input[i];
+        let next_cup = input[i + 1];
+
+        cups[cup] = next_cup;
+    }
+
+    // Initialize cup zero, used as the 'current cup' later
+    cups[0] = input[0];
+
+    // Connect the ends
+    // The last from the input, points to the first autogenerated cup
+    cups[input[input.len() - 1]] = input.len() + 1;
+
+    let idx = cups.len() - 1;
+    cups[idx] = input[0];
+
+    for _ in 1..10_000_001 {
+        let cur_cup = cups[0];
+
+        let taken1 = cups[cur_cup];
+        let taken2 = cups[taken1];
+        let taken3 = cups[taken2];
+        cups[cur_cup] = cups[taken3];
+        cups[0] = cups[taken3];
+
+        let mut dest = cur_cup;
+        while dest == taken1 || dest == taken2 || dest == taken3 || dest == cur_cup {
+            dest = if dest - 1 == 0 { cup_count } else { dest - 1 }
+        }
+
+        let cut = cups[dest];
+        cups[dest] = taken1;
+        cups[taken3] = cut;
+    }
+
+    let a = cups[1];
+    let b = cups[a];
+
+    println!("Cups: {} {}", a, b);
+
+    let answer = a * b;
+    println!("Answer: {}", answer);
+
+    Ok(())
+}
+
+#[cfg(test)]
+mod tests {
+    use crate::*;
+}