From 1c41e885ad262fef7bc60d13a5264c4b9a8f459b Mon Sep 17 00:00:00 2001
From: "max.nuding" <max.nuding@uni-konstanz.de>
Date: Mon, 12 Dec 2022 13:35:34 +0100
Subject: [PATCH] refactor coord checking

---
 src/day12/mod.rs | 116 ++++++++++++++++++++++-------------------------
 1 file changed, 54 insertions(+), 62 deletions(-)

diff --git a/src/day12/mod.rs b/src/day12/mod.rs
index c43f20c..21b2de6 100644
--- a/src/day12/mod.rs
+++ b/src/day12/mod.rs
@@ -3,8 +3,8 @@ use itertools::Itertools;
 
 #[derive(Debug, PartialEq, Eq, Clone, Hash, Default)]
 struct Coord {
-    pub row: i32,
-    pub col: i32,
+    pub row: usize,
+    pub col: usize,
 }
 
 pub fn run() {
@@ -20,19 +20,19 @@ pub fn run() {
                 .map(|(col, c)| match c {
                     'S' => {
                         start = Coord {
-                            row: r as i32,
-                            col: col as i32,
+                            row: r,
+                            col,
                         };
                         0
                     }
                     'E' => {
                         target = Coord {
-                            row: r as i32,
-                            col: col as i32,
+                            row: r,
+                            col,
                         };
                         25
                     }
-                    c => (c as u32) - ('a' as u32),
+                    c => (c as u8) - ('a' as u8),
                 })
                 .collect_vec()
         })
@@ -40,7 +40,7 @@ pub fn run() {
 
     #[cfg(feature = "part1")]
     {
-        println!("Day 12, Part 01: {:?}", bfs(&map, start, target.clone()));
+        println!("Day 12, Part 01: {:?}", bfs(&map, start, target.clone()).unwrap());
     }
 
     #[cfg(feature = "part2")]
@@ -53,8 +53,8 @@ pub fn run() {
                     .enumerate()
                     .filter(|(_, vv)| **vv == 0)
                     .map(|(col, _)| Coord {
-                        row: row as i32,
-                        col: col as i32,
+                        row,
+                        col,
                     })
                     .collect_vec()
             })
@@ -62,12 +62,13 @@ pub fn run() {
         let min = starting_points
             .iter()
             .filter_map(|start| bfs(&map, start.clone(), target.clone()))
-            .min();
+            .min()
+            .unwrap();
         println!("Day 12, Part 02: {:?}", min);
     }
 }
 
-fn bfs(map: &Vec<Vec<u32>>, start: Coord, target: Coord) -> Option<usize> {
+fn bfs(map: &Vec<Vec<u8>>, start: Coord, target: Coord) -> Option<usize> {
     let mut visited = vec![vec![false; map[0].len()]; map.len()];
     let mut queue = std::collections::VecDeque::new();
     queue.push_back((start, 0));
@@ -76,62 +77,53 @@ fn bfs(map: &Vec<Vec<u32>>, start: Coord, target: Coord) -> Option<usize> {
         if next == target {
             return Some(path_length);
         }
-        let up = Coord {
-            row: next.row - 1,
-            col: next.col,
-        };
-        let down = Coord {
-            row: next.row + 1,
-            col: next.col,
-        };
-        let left = Coord {
-            row: next.row,
-            col: next.col - 1,
-        };
-        let right = Coord {
-            row: next.row,
-            col: next.col + 1,
-        };
-        let can_down = check_bounds(&down, map)
-            && !visited[down.row as usize][down.col as usize]
-            && map[next.row as usize][next.col as usize] + 1
-                >= map[down.row as usize][down.col as usize];
-        if can_down {
-            visited[down.row as usize][down.col as usize] = true;
-            queue.push_back((down, path_length + 1));
+        match make_coord((next.row as isize) + 1, next.col as isize, &map, &visited) {
+            Some(down) if map[next.row][next.col] + 1
+                >= map[down.row][down.col] => {
+                visited[down.row][down.col] = true;
+                queue.push_back((down, path_length + 1));
+            },
+            _ => {}
         }
-        let can_up = check_bounds(&up, map)
-            && !visited[up.row as usize][up.col as usize]
-            && map[next.row as usize][next.col as usize] + 1
-                >= map[up.row as usize][up.col as usize];
-        if can_up {
-            visited[up.row as usize][up.col as usize] = true;
-            queue.push_back((up, path_length + 1));
+        match make_coord((next.row as isize) - 1, next.col as isize, &map, &visited) {
+            Some(up) if map[next.row][next.col] + 1
+                >= map[up.row][up.col] => {
+                visited[up.row][up.col] = true;
+                queue.push_back((up, path_length + 1));
+            },
+            _ => {}
         }
-        let can_left = check_bounds(&left, map)
-            && !visited[left.row as usize][left.col as usize]
-            && map[next.row as usize][next.col as usize] + 1
-                >= map[left.row as usize][left.col as usize];
-        if can_left {
-            visited[left.row as usize][left.col as usize] = true;
-            queue.push_back((left, path_length + 1));
+        match make_coord(next.row as isize, (next.col as isize) - 1, &map, &visited) {
+            Some(left) if map[next.row][next.col] + 1
+                >= map[left.row][left.col] => {
+                visited[left.row][left.col] = true;
+                queue.push_back((left, path_length + 1));
+            },
+            _ => {}
         }
-        let can_right = check_bounds(&right, map)
-            && !visited[right.row as usize][right.col as usize]
-            && map[next.row as usize][next.col as usize] + 1
-                >= map[right.row as usize][right.col as usize];
-        if can_right {
-            visited[right.row as usize][right.col as usize] = true;
-            queue.push_back((right, path_length + 1));
+        match make_coord(next.row as isize, (next.col as isize) + 1, &map, &visited) {
+            Some(right) if map[next.row][next.col] + 1
+                >= map[right.row][right.col] => {
+                visited[right.row][right.col] = true;
+                queue.push_back((right, path_length + 1));
+            },
+            _ => {}
         }
     }
     None
 }
 
-fn check_bounds(coord: &Coord, map: &Vec<Vec<u32>>) -> bool {
-    coord.row >= 0
-        && coord.col >= 0
-        && coord.row < map.len() as i32
-        && coord.row < map.len() as i32
-        && coord.col < map[coord.row as usize].len() as i32
+fn make_coord(row: isize, col: isize, map: &Vec<Vec<u8>>, visited: &Vec<Vec<bool>>) -> Option<Coord> {
+    if row >= 0
+        && col >= 0
+        && row < map.len() as isize
+        && (col as usize) < map[row as usize].len()
+        && !visited[row as usize][col as usize] {
+        Some(Coord {
+            row: row as usize,
+            col: col as usize
+        })
+    } else {
+        None
+    }
 }