day10 part2

2 files changed, 108 insertions, 24 deletions

diff --git a/2023/day10.rs b/2023/day10.rs
index 919223c..4ad319e 100644
--- a/2023/day10.rs
+++ b/2023/day10.rs
@@ -1,6 +1,4 @@
 #![allow(dead_code)]
-#![allow(unused_variables)]
-#![allow(unused_mut)]
 use num::complex::Complex as c;
 use num::Complex;
 use std::fs::File;
@@ -18,6 +16,13 @@ enum Dir {
     Ground,
 }
 
+#[derive(Debug, PartialEq, Clone, Copy)]
+enum Flood {
+    Pipe,
+    Empty,
+    Full,
+}
+
 const LUT: [(Dir, Complex<i32>, Complex<i32>, char, char); 8] = [
     (Dir::UD, c::new(0, 1), c::new(0, -1), '|', '│'),
     (Dir::LR, c::new(1, 0), c::new(-1, 0), '-', '─'),
@@ -48,9 +53,24 @@ fn print_m(m: &Vec<Vec<Dir>>) {
     println!();
 }
 
+fn print_m2(m: &Vec<Vec<Flood>>) {
+    for j in 0..m.len() {
+        for i in 0..m[0].len() {
+            let a = match m[j][i] {
+                Flood::Pipe => '#',
+                Flood::Empty => ' ',
+                Flood::Full => '.',
+            };
+            print!("{}", a);
+        }
+        println!();
+    }
+    println!();
+}
+
 fn find_start(m: &Vec<Vec<Dir>>) -> Complex<i32> {
-    for x in 0..m.len() {
-        for y in 0..m[0].len() {
+    for y in 0..m.len() {
+        for x in 0..m[0].len() {
             if m[y][x] == Dir::Start {
                 return (x as i32) + (y as i32) * c::i();
             }
@@ -80,6 +100,24 @@ fn next(
     (pos, dir)
 }
 
+fn flood(mut m: Vec<Vec<Flood>>) -> (Vec<Vec<Flood>>, usize) {
+    let mut changes = 0;
+    for y in 1..m.len() - 1 {
+        for x in 1..m[0].len() - 1 {
+            if m[y][x] == Flood::Full {
+                for (yy, xx) in [(y - 1, x), (y + 1, x), (y, x + 1), (y, x - 1)] {
+                    if m[yy][xx] == Flood::Empty {
+                        changes += 1;
+                        m[yy][xx] = Flood::Full;
+                    }
+                }
+            }
+        }
+    }
+
+    (m, changes)
+}
+
 fn main() {
     // let filename = "in/day10.ref";
     let filename = "in/day10.pzl";
@@ -89,38 +127,79 @@ fn main() {
     f.read_to_string(&mut content).expect("cannot read file");
     let lines = content.trim_end().split('\n');
 
-    let mut m: Vec<Vec<Dir>> = Vec::new();
+    let mut m1: Vec<Vec<Dir>> = Vec::new();
     for line in lines {
         let mut r = Vec::new();
         for c in line.chars() {
-            for m in LUT {
-                if m.3 == c {
-                    r.push(m.0);
+            for m1 in LUT {
+                if m1.3 == c {
+                    r.push(m1.0);
                 }
             }
         }
-        m.push(r);
+        m1.push(r);
     }
+    // print_m(&m1);
 
-    let mut res1 = 0;
-    let mut res2 = 0;
-
-    print_m(&m);
-    let start = find_start(&m);
+    let start = find_start(&m1);
 
     let mut pos = start;
     let mut dir = c::new(1, 0);
 
-    (pos, dir) = next(pos, dir, &m);
-    res1 += 1;
+    let mut path: Vec<(usize, usize)> = Vec::new();
 
-    while pos != start {
-        (pos, dir) = next(pos, dir, &m);
+    let mut res1 = 0;
+    loop {
+        path.push((pos.re as usize, pos.im as usize));
+        (pos, dir) = next(pos, dir, &m1);
         res1 += 1;
+        if pos == start {
+            break;
+        }
     }
+    path.push((pos.re as usize, pos.im as usize));
     res1 /= 2;
-    println!("{} {}", pos, dir);
+
+    let mut m2: Vec<Vec<Flood>> = vec![vec![Flood::Empty; 2 * m1[0].len() + 4]; 2 * m1.len() + 4];
+
+    for ((x0, y0), (x1, y1)) in path.iter().zip(path.iter().skip(1)) {
+        m2[*y0 * 2 + 2][*x0 * 2 + 2] = Flood::Pipe;
+        m2[*y0 + *y1 + 2][*x0 + *x1 + 2] = Flood::Pipe;
+    }
+
+    for y in 0..m2.len() {
+        let l = m2[0].len() - 1;
+        m2[y][0] = Flood::Full;
+        m2[y][1] = Flood::Full;
+        m2[y][l - 1] = Flood::Full;
+        m2[y][l] = Flood::Full;
+    }
+    for x in 0..m2[0].len() {
+        let l = m2.len() - 1;
+        m2[0][x] = Flood::Full;
+        m2[1][x] = Flood::Full;
+        m2[l - 1][x] = Flood::Full;
+        m2[l][x] = Flood::Full;
+    }
+
+    // print_m2(&m2);
+    let mut changes = 1;
+    while changes != 0 {
+        (m2, changes) = flood(m2);
+    }
+    // print_m2(&m2);
+
+    let mut res2 = 0;
+    for y in (2..m2.len()).step_by(2) {
+        for x in (2..m2[0].len()).step_by(2) {
+            if m2[y][x] == Flood::Empty {
+                res2 += 1;
+            }
+        }
+    }
 
     println!("res1: {}", res1);
     println!("res2: {}", res2);
+    assert_eq!(res1, 6778);
+    assert_eq!(res2, 433);
 }
diff --git a/2023/in/day10.ref b/2023/in/day10.ref
index 3aea4dd..adaae96 100644
--- a/2023/in/day10.ref
+++ b/2023/in/day10.ref
@@ -1,5 +1,10 @@
-7-F7-
-.FJ|7
-SJLL7
-|F--J
-LJ.LJ
+.F----7F7F7F7F-7....
+.|F--7||||||||FJ....
+.||.FJ||||||||L7....
+FJL7L7LJLJ||LJ.L-7..
+L--J.L7...LJS7F-7L7.
+....F-J..F7FJ|L7L7L7
+....L7.F7||L7|.L7L7|
+.....|FJLJ|FJ|F7|.LJ
+....FJL-7.||.||||...
+....L---J.LJ.LJLJ...