Day 12

res/12/input.txt

@@ -0,0 +1,41 @@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src/days/d12.rs

@@ -0,0 +1,130 @@
+use std::{fs, collections::{HashMap, HashSet}};
+
+pub fn solve() {
+    let path = "res/12/input.txt";
+
+    let contents = fs::read_to_string(path).expect("I/O error, wrong path?");
+
+    let lines: Vec<&str> = contents
+        .lines()
+        .collect();
+
+    // Build grid
+    let mut start = (0, 0);
+    let mut end = (0, 0);
+    let grid: Vec<Vec<u32>> = lines.iter().enumerate().map(|(y, line)| {
+        line.chars().enumerate().map(|(x, c)|
+            match c {
+                'S' => {
+                    start = (x as u32, y as u32);
+                    return char_to_numeric('a')
+
+                },
+                'E' => {
+                    end = (x as u32, y as u32);
+                    return char_to_numeric('z')
+                },
+                _ => {
+                    return char_to_numeric(c)
+                }
+        }).collect()
+    }).collect();
+
+    // Build adjacent lists
+    let mut adjacents = HashMap::<(u32,u32),Vec<(u32,u32)>>::new();
+
+    grid.iter()
+        .enumerate()
+        .for_each(|(y, line)| {
+        line.iter()
+            .enumerate()
+            .for_each(|(x, height)| {
+            adjacents.insert((x as u32, y as u32), Vec::<(u32,u32)>::new());
+            // top
+            if y != 0 && grid[y-1][x] <= height+1 {
+                adjacents.get_mut(&(x as u32, y as u32)).unwrap().push((x as u32, (y-1) as u32))
+            }
+            // bot
+            if y != grid.len()-1 && grid[y+1][x] <= height+1 {
+                adjacents.get_mut(&(x as u32, y as u32)).unwrap().push((x as u32, (y+1) as u32))
+            }
+            //left
+            if x != 0 && grid[y][x-1] <= height+1 {
+                adjacents.get_mut(&(x as u32, y as u32)).unwrap().push(((x-1) as u32, y as u32))
+            }
+            // right
+            if x != grid[0].len()-1 && grid[y][x+1] <= height+1 {
+                adjacents.get_mut(&(x as u32, y as u32)).unwrap().push(((x+1) as u32, y as u32))
+            }
+        })
+    });
+
+    // task 1 - find min distance between start and end
+    let res = bfs(start, end, &adjacents);
+
+    println!("Result 1: {res}");
+
+    // task 2 - find min distance for each node with height 1, select min
+    let mut distances = Vec::<i32>::new();
+    grid.iter()
+        .enumerate()
+        .for_each(|(y, line)| {
+        line.iter()
+            .enumerate()
+            .for_each(|(x, height)| {
+            if *height == 1 {
+                distances.push(
+                    bfs((x as u32, y as u32), end, &adjacents)
+                )
+            }
+        })
+    });
+    let res = *distances.iter()
+        .filter(|dist| **dist != -1)
+        .min()
+        .unwrap();
+    
+    println!("Result 2: {res}")
+
+}
+
+// Maps lowercase chars to 1..=26
+fn char_to_numeric(c: char) -> u32 {
+    (c as u32) - ('a' as u32) + 1
+}
+
+// Runs a Breadth-first search on the given graph and returns the minimal steps necessary to reach end from start, -1 if not reachable
+fn bfs(start: (u32,u32), end: (u32,u32), adjacents: &HashMap<(u32,u32),Vec<(u32,u32)>>) -> i32 {
+    let mut queue = Vec::<(u32,u32)>::new();
+    let mut seen_nodes = HashSet::<(u32,u32)>::new();
+    let mut predecessor = HashMap::<(u32,u32),(u32,u32)>::new();
+    queue.push(start);
+    seen_nodes.insert(start);
+    while !queue.is_empty() {
+        let node = queue.remove(0);
+        if node == end {
+            break;
+        }
+        adjacents.get(&node).unwrap()
+            .iter()
+            .for_each(|child| {
+                if !seen_nodes.contains(child) {
+                    queue.push(*child);
+                    seen_nodes.insert(*child);
+                    predecessor.insert(*child, node);
+                }
+            })
+    }
+    // if end is reachable, it now is in predecessor
+    let mut res = 0; // steps
+    let mut node = end;
+    while node != start {
+        node = match predecessor.get(&node) {
+            Some(n) => *n,
+            None => return -1 // return -1 if end not reachable
+        };
+        res += 1;
+    }
+
+    res
+}

src/main.rs

@@ -1,7 +1,7 @@
 pub mod days;
 
 fn main() {
-    days::d11::solve()
+    days::d12::solve()
     //_all_days()
 }
 
@@ -26,4 +26,8 @@ fn _all_days() {
     days::d09::solve();
     println!("\nDay 10");
     days::d10::solve();
+    println!("\nDay 11");
+    days::d11::solve();
+    println!("\nDay 12");
+    days::d12::solve();
 }