From 3621b8231a603854e6c088df2879bae02e62681d Mon Sep 17 00:00:00 2001
From: Yigit Sever
Date: Mon, 20 Dec 2021 15:56:27 +0300
Subject: 2021, day9: part2

---
 2021/day9/src/main.rs | 120 ++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 120 insertions(+)

diff --git a/2021/day9/src/main.rs b/2021/day9/src/main.rs
index 75bf1e9..3c8d4c6 100644
--- a/2021/day9/src/main.rs
+++ b/2021/day9/src/main.rs
@@ -1,11 +1,25 @@
+use std::collections::HashSet;
 use std::env;
 use std::fs::File;
 use std::io::{BufRead, BufReader};
 
+#[derive(Debug, Clone, Copy, Eq, PartialEq, Hash)]
+struct Point {
+    x: usize,
+    y: usize,
+    height: u32,
+}
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct Basin {
+    points: HashSet<Point>,
+}
+
 fn main() {
     let reader = open_file();
 
     let mut points: Vec<Vec<u32>> = Vec::new();
+    let mut basins: Vec<Basin> = Vec::new();
 
     for line in reader.lines() {
         points.push(
@@ -46,9 +60,115 @@ fn main() {
             };
             if num < up && num < down && num < right && num < left {
                 risk_level += 1 + *num;
+                basins.push(Basin {
+                    points: HashSet::from_iter(vec![Point {
+                        x: idx,
+                        y: ndx,
+                        height: *num,
+                    }]),
+                });
+            }
+        }
+    }
+
+    // TODO: fix this maybe because i hate it <20-12-21, yigit> //
+    for basin in basins.iter_mut() {
+        let mut stack: Vec<Point> = Vec::new();
+        stack.extend(basin.points.clone().into_iter());
+
+        while !stack.is_empty() {
+            let minibasin = stack.pop().unwrap();
+
+            let up = points
+                .get(((minibasin.x as isize) - 1) as usize)
+                .unwrap_or_else(|| &nine)
+                .get(minibasin.y)
+                .unwrap_or_else(|| &9);
+
+            let down = match points.get(minibasin.x + 1) {
+                Some(line) => match line.get(minibasin.y) {
+                    Some(number) => number,
+                    None => &9,
+                },
+                None => &9,
+            };
+            let left = match points.get(minibasin.x) {
+                Some(line) => match line.get(((minibasin.y as isize) - 1) as usize) {
+                    Some(number) => number,
+                    None => &9,
+                },
+                None => &9,
+            };
+            let right = match points.get(minibasin.x) {
+                Some(line) => match line.get(minibasin.y + 1) {
+                    Some(number) => number,
+                    None => &9,
+                },
+                None => &9,
+            };
+
+            if up != &9 {
+                let p = Point {
+                    x: minibasin.x - 1,
+                    y: minibasin.y,
+                    height: *up,
+                };
+
+                if !basin.points.contains(&p) {
+                    stack.push(p);
+                    basin.points.insert(p);
+                }
+            }
+
+            if down != &9 {
+                let p = Point {
+                    x: minibasin.x + 1,
+                    y: minibasin.y,
+                    height: *down,
+                };
+
+                if !basin.points.contains(&p) {
+                    stack.push(p);
+                    basin.points.insert(p);
+                }
+            }
+
+            if left != &9 {
+                let p = Point {
+                    x: minibasin.x,
+                    y: minibasin.y - 1,
+                    height: *left,
+                };
+
+                if !basin.points.contains(&p) {
+                    stack.push(p);
+                    basin.points.insert(p);
+                }
+            }
+
+            if right != &9 {
+                let p = Point {
+                    x: minibasin.x,
+                    y: minibasin.y + 1,
+                    height: *right,
+                };
+
+                if !basin.points.contains(&p) {
+                    stack.push(p);
+                    basin.points.insert(p);
+                }
             }
         }
     }
+
+    let mut lens: Vec<usize> = basins.iter().map(|x| x.points.len()).collect();
+
+    lens.sort();
+    lens.reverse();
+
+    let foo: usize = lens.iter().take(3).product();
+
+    println!("{}", foo);
     println!("{}", risk_level);
 }
 
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