2023-08: Attempt part two

input/2023/day_08/input_test_part_2.txt

@@ -0,0 +1,10 @@
+LR
+
+11A = (11B, XXX)
+11B = (XXX, 11Z)
+11Z = (11B, XXX)
+22A = (22B, XXX)
+22B = (22C, 22C)
+22C = (22Z, 22Z)
+22Z = (22B, 22B)
+XXX = (XXX, XXX)

src/year_2023/day_08_haunted_wasteland/common.rs

@@ -0,0 +1,23 @@
+#[derive(Clone)]
+pub struct Node {
+    pub value: String,
+    pub left: String,
+    pub right: String,
+}
+
+pub fn parse_line(s: &str) -> Node {
+    // AAA = (BBB, CCC)
+    let s1: Vec<&str> = s.split('=').collect();
+    let node_val = s1[0].trim();
+
+    let s2 = s1[1].replace(&['(', ')'], "");
+    let s3: Vec<&str> = s2.trim().split(',').collect();
+    let node_left = s3[0].trim();
+    let node_right = s3[1].trim();
+
+    Node {
+        value: node_val.to_string(),
+        left: node_left.to_string(),
+        right: node_right.to_string(),
+    }
+}

src/year_2023/day_08_haunted_wasteland/mod.rs

@@ -1,5 +1,6 @@
+pub mod common;
 pub mod part_one;
-// pub mod part_two;
+pub mod part_two;
 
 use crate::utils::solution::Solution;
 
@@ -15,6 +16,6 @@ impl Solution for Day8Solution {
     fn part_two(&self) -> String {
         // Implementation for part two of day 1
         // ...
-        String::from("Not implemented")
+        part_two::part_two()
     }
 }

src/year_2023/day_08_haunted_wasteland/part_one.rs

@@ -1,12 +1,7 @@
 use std::collections::HashMap;
 
 use crate::utils::input_reader;
-
-pub struct Node {
-    pub value: String,
-    pub left: String,
-    pub right: String,
-}
+use crate::year_2023::day_08_haunted_wasteland::common::{parse_line, Node};
 
 pub fn part_one() -> String {
     if let Ok(lines) = input_reader::read_lines("./input/2023/day_08/input.txt") {
@@ -50,20 +45,3 @@ pub fn part_one() -> String {
         panic!("Failed to read lines from input file");
     }
 }
-
-pub fn parse_line(s: &str) -> Node {
-    // AAA = (BBB, CCC)
-    let s1: Vec<&str> = s.split('=').collect();
-    let node_val = s1[0].trim();
-
-    let s2 = s1[1].replace(&['(', ')'], "");
-    let s3: Vec<&str> = s2.trim().split(',').collect();
-    let node_left = s3[0].trim();
-    let node_right = s3[1].trim();
-
-    Node {
-        value: node_val.to_string(),
-        left: node_left.to_string(),
-        right: node_right.to_string(),
-    }
-}

src/year_2023/day_08_haunted_wasteland/part_two.rs

@@ -0,0 +1,72 @@
+use std::collections::HashMap;
+
+use crate::utils::input_reader;
+use crate::year_2023::day_08_haunted_wasteland::common::{parse_line, Node};
+
+pub fn part_two() -> String {
+    if let Ok(lines) = input_reader::read_lines("./input/2023/day_08/input_test_part_2.txt") {
+        let mut node_map: HashMap<String, &Node> = HashMap::new();
+        let mut start_nodes: Vec<&Node> = Vec::new();
+        let mut instructions: Vec<char> = Vec::new();
+        let mut s: String;
+
+        for (i, line) in lines.enumerate() {
+            s = line.unwrap();
+
+            if i == 0 {
+                instructions = s.chars().collect();
+                continue;
+            }
+
+            if s.is_empty() {
+                continue;
+            }
+
+            let node = parse_line(&s);
+            let value = node.value.clone();
+
+            node_map.insert(value.clone(), &node.clone());
+
+            if value.ends_with('A') {
+                let cloned_node = node.clone();
+                start_nodes.push(&cloned_node);
+            }
+        }
+
+        let mut curr_nodes: Vec<&Node> = start_nodes;
+        let mut count = 0;
+        let mut cond = true;
+
+        while cond {
+            let i = count % instructions.len();
+            let c = instructions[i];
+
+            let mut new_curr: Vec<&Node> = Vec::new();
+            cond = false;
+
+            for n in curr_nodes {
+                let nn: &Node;
+                if instructions[i] == 'L' {
+                    nn = &node_map[&n.left];
+                } else if instructions[i] == 'R' {
+                    nn = &node_map[&n.right];
+                } else {
+                    panic!("Unknown instruction!")
+                }
+
+                if !nn.value.clone().ends_with('Z') {
+                    cond = true;
+                }
+
+                new_curr.push(nn);
+            }
+
+            curr_nodes = new_curr;
+            count += 1;
+        }
+
+        return count.to_string();
+    } else {
+        panic!("Failed to read lines from input file");
+    }
+}