From ea761135bb8002049b4bb001402e3b1749b80494 Mon Sep 17 00:00:00 2001
From: Baipyrus <simon.waltemathe@gmail.com>
Date: Sun, 28 Jan 2024 00:03:40 +0100
Subject: [PATCH] failed attempt at A* pathfinding, no clue

---
 src/day17/mod.rs | 75 ++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 75 insertions(+)

diff --git a/src/day17/mod.rs b/src/day17/mod.rs
index 08cd667..2f3a85c 100644
--- a/src/day17/mod.rs
+++ b/src/day17/mod.rs
@@ -9,11 +9,78 @@ pub fn part_one() {
 }
 
 fn pathfind(grid: &mut Vec<Vec<Block>>) -> i32 {
+    let mut closed: Vec<&mut Block> = Vec::new();
+    let (end, mut open);
+    {
+        let result = init_pos(grid);
+        end = result.0;
+        open = result.1;
+    };
+
+    while !open.is_empty() {
+        let mut current = None;
+        let mut index = 0;
+        let mut record = std::i32::MAX;
+
+        // Get best distance + heuristic
+        for (i, next) in open.iter().enumerate() {
+            let score = next.d + next.h;
+            if score < record {
+                record = score;
+                index = i;
+            }
+        }
+
+        // Remove current from open set
+        current = Some(open.remove(index));
+
+        if let Some(current) = current {
+            // Break if current is end
+            if current.compare(end) {
+                break;
+            }
+
+            // Scan neighbors, limit straight line length
+            // Add neighbors to open set
+            for (j, line) in grid.iter_mut().enumerate() {
+                for (i, next) in line.iter_mut().enumerate() {
+                    if !closed.contains(&next) && !open.contains(&next) {
+                        next.d = current.d + next.c;
+                        next.h = next.distance(end);
+                        open.push(next);
+                    }
+                }
+            }
+
+            // Add current to closed set
+            closed.push(current);
+        }
+    }
+
+    end.d
+}
+
+fn init_pos(grid: &mut Vec<Vec<Block>>) -> (&mut Block, Vec<&mut Block>) {
+    let mut open = Vec::new();
+
+    let middle = grid.len() / 2;
+    let (top, bottom) = grid.split_at_mut(middle);
+
+    let start = top.first_mut().unwrap().first_mut().unwrap();
+    let end = bottom.last_mut().unwrap().last_mut().unwrap();
+
+    start.h = start.distance(end) as i32;
+    open.push(start);
+
+    (end, open)
 }
 
 struct Block {
     x: usize,
     y: usize,
+    c: i32,
+    d: i32,
+    h: i32,
 }
 
 impl Block {
@@ -28,6 +95,14 @@ impl Block {
     }
 }
 
+impl PartialEq for Block {
+    fn eq(&self, other: &Self) -> bool {
+        self.compare(other)
+    }
+}
+
+impl Eq for Block {}
+
 fn setup() -> Vec<Vec<Block>> {
     let name = "day17";
     println!("Executing module '{name}' entrypoint . . . ");