Day 7 puzzle

Cargo.lock

@@ -12,6 +12,7 @@ dependencies = [
  "day4",
  "day5",
  "day6",
+ "day7",
 ]
 
 [[package]]
@@ -37,3 +38,7 @@ version = "0.1.0"
 [[package]]
 name = "day6"
 version = "0.1.0"
+
+[[package]]
+name = "day7"
+version = "0.1.0"

Cargo.toml

@@ -17,3 +17,4 @@ day3 = { path = "./day3" }
 day4 = { path = "./day4" }
 day5 = { path = "./day5" }
 day6 = { path = "./day6" }
+day7 = { path = "./day7" }

day7/Cargo.toml

@@ -0,0 +1,8 @@
+[package]
+name = "day7"
+version = "0.1.0"
+edition = "2021"
+
+# See more keys and their definitions at https://doc.rust-lang.org/cargo/reference/manifest.html
+
+[dependencies]

day7/src/lib.rs

@@ -0,0 +1,78 @@
+use std::collections::HashMap;
+
+const ROOT: &str = "/";
+const TOTAL_SPACE: u64 = 70_000_000;
+const UPDATE_SPACE: u64 = 30_000_000;
+
+pub fn start() {
+	let input = include_str!("input.txt").replace("\r", "");
+
+	let input = input.lines().collect::<Vec<&str>>();
+	let dirs = get_dirs(input);
+
+	let sum1: u64 = dirs
+		.iter()
+		.filter_map(|(_, &size)| {
+			if size <= 100_000 {
+				Some(size)
+			}
+			else {
+				None
+			}
+		})
+		.sum();
+	println!("Part 1: {}", sum1);
+
+	let used_space: u64 = dirs[ROOT];
+	let free_space = TOTAL_SPACE - used_space;
+	let needed_space = UPDATE_SPACE - free_space;
+
+	let mut dirs = dirs
+		.iter()
+		.filter_map(|(_, &size)| {
+			if size >= needed_space {
+				Some(size)
+			}
+			else {
+				None
+			}
+		})
+		.collect::<Vec<_>>();
+	dirs.sort();
+	println!("Part 2: {}", dirs[0])
+}
+
+fn get_dirs(lines: Vec<&str>) -> HashMap<String, u64> {
+	let mut cwd: Vec<String> = vec![];
+	let mut dirs: HashMap<String, u64> = HashMap::new();
+
+	for cmd in lines {
+		if cmd.starts_with("$ cd") {
+			match &cmd[5..] {
+				"/" => {
+					cwd = vec![ROOT.to_string()];
+				}
+				".." => {
+					cwd.pop();
+				}
+				x => {
+					cwd.push(x.to_string());
+				}
+			}
+		}
+		else if cmd.starts_with("$ ls") || cmd.starts_with("dir") {
+			continue;
+		}
+		else {
+			let (size, _) = cmd.split_once(" ").unwrap();
+			let size = size.parse::<u64>().unwrap();
+
+			for i in 0..cwd.len() {
+				let key = cwd[0..=i].join("/").to_string();
+				dirs.entry(key).and_modify(|a| *a += size).or_insert(size);
+			}
+		}
+	}
+
+	dirs
+}

src/main.rs

@@ -1,9 +1,4 @@
 
 fn main() {
-	// day1::start();
-    // day2::start();
-	// day3::start();
-	// day4::start();
-	// day5::start();
-	day6::start();
+	day7::start();
 }