day 5

d5/Cargo.lock

@@ -0,0 +1,7 @@
+# This file is automatically @generated by Cargo.
+# It is not intended for manual editing.
+version = 3
+
+[[package]]
+name = "d5"
+version = "0.1.0"

d5/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "d5"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

d5/src/main.rs

@@ -0,0 +1,65 @@
+use std::{fs::read_to_string, io::Result};
+
+fn main() -> Result<()> {
+    let mut stacks = Vec::new();
+    let mut stacks2 = Vec::new();
+
+    for line in read_to_string("input.txt")?.split("\n") {
+        if line.is_empty() {
+            continue;
+        }
+
+        let bytes = line.as_bytes();
+
+        if bytes[0] == 0x5b {
+            // row of crates
+            let len = (bytes.len() + 1) / 4;
+            while stacks.len() < len {
+                stacks.push(Vec::new())
+            }
+            for i in 0..len {
+                let c = bytes[4 * i + 1] as char;
+                if c == ' ' {
+                    continue;
+                }
+                stacks[i].insert(0, c);
+            }
+        } else if bytes[0] == 0x20 {
+            // crate ids
+            stacks2 = stacks.clone();
+        } else {
+            // move op
+            let parts = line.split(" ").collect::<Vec<_>>();
+            let count = parts[1].parse().unwrap();
+            let src: usize = parts[3].parse().unwrap();
+            let dst: usize = parts[5].parse().unwrap();
+            for _ in 0..count {
+                let item = stacks[src - 1].pop().unwrap();
+                stacks[dst - 1].push(item);
+            }
+
+            let src_len = stacks2[src - 1].len();
+            let mut collected = stacks2[src - 1]
+                .drain(src_len - count..)
+                .collect::<Vec<_>>();
+            collected.drain(..).for_each(|x| stacks2[dst - 1].push(x));
+        }
+    }
+
+    println!(
+        "Part 1: {}",
+        stacks
+            .iter()
+            .map(|stack| stack[stack.len() - 1])
+            .collect::<String>()
+    );
+    println!(
+        "Part 2: {}",
+        stacks2
+            .iter()
+            .map(|stack| stack[stack.len() - 1])
+            .collect::<String>()
+    );
+
+    Ok(())
+}