From 8991100b598f140c13969732e63616b7686e8c56 Mon Sep 17 00:00:00 2001
From: Joseph Montanaro <jfmonty2@gmail.com>
Date: Tue, 14 Dec 2021 21:08:49 -0800
Subject: [PATCH] completely rework day 9, still broken though

---
 2021/src/day9.rs | 127 +++++++++++++++++++++--------------------------
 2021/src/lib.rs  |  22 +++++---
 2 files changed, 70 insertions(+), 79 deletions(-)

diff --git a/2021/src/day9.rs b/2021/src/day9.rs
index 90bcb96..b6f5182 100644
--- a/2021/src/day9.rs
+++ b/2021/src/day9.rs
@@ -1,23 +1,24 @@
 use color_eyre::eyre;
 use eyre::eyre;
 
+use crate::lib::Vec2;
 
-// #[derive(Eq, PartialEq)]
-enum Elevation {
-    High,
-    Mid,
-    Low,
+
+#[derive(Debug)]
+struct Cell {
+    height: u32,
+    min: bool,
 }
-use Elevation::*;
 
 
-fn load(data: &str) -> eyre::Result<Vec<Vec<u32>>> {
-    let mut heights = Vec::new();
+fn load(data: &str) -> eyre::Result<Vec2<Cell>> {
+    let num_columns = data.lines().next().unwrap().len();
+    let mut heights = Vec2::new(num_columns);
     for line in data.lines() {
         let mut row = Vec::new();
         for c in line.chars() {
             match c.to_digit(10) {
-                Some(d) => row.push(d),
+                Some(d) => row.push(Cell {height: d, min: true}),
                 None => return Err(eyre!("Invalid character (not a digit): {}", c)),
             }
         }
@@ -27,79 +28,63 @@ fn load(data: &str) -> eyre::Result<Vec<Vec<u32>>> {
 }
 
 
-fn cmp_horizontal(row: &[u32], pos: usize) -> Elevation {
-    let prev = if pos == 0 {None} else {Some(row[pos - 1])};
-    let next = if pos == row.len() - 1 {None} else {Some(row[pos + 1])};
-    let current = row[pos];
-
-    if current > prev.unwrap_or(0) && current > next.unwrap_or(0) {
-        High
-    }
-    else if current < prev.unwrap_or(9) && current < next.unwrap_or(9) {
-        Low
-    }
-    else {
-        Mid
-    }
-}
-
-
-fn scan(map: &[Vec<u32>]) -> Vec<Vec<Elevation>> {
-    let mut result: Vec<Vec<Elevation>> = Vec::new();
-    for (r, row) in map.iter().enumerate() {
-        let mut scanned_row = Vec::new();
-        for (col, height) in row.iter().enumerate() {
-            let elev = match cmp_horizontal(row, col) {
-                High => {
-                    if r == 0 || height > &map[r - 1][col] {
-                        High
+fn scan(map: &mut Vec2<Cell>) {
+    for r in 0..map.row_count() {
+        for col in 0..map.col_count() {
+            if col > 0 {
+                if map[r][col].height <= map[r][col - 1].height {
+                    map[r][col - 1].min = false;
+                    if map[r][col].height == map[r][col - 1].height {
+                        map[r][col].min = false;
                     }
-                    else {
-                        Mid
-                    }
-                },
-                Low => {
-                    if r == 0 || height < &map[r - 1][col] {
-                        Low
-                    }
-                    else {
-                        Mid
-                    }
-                },
-                Mid => Mid,
-            };
-
-            if r > 0 {
-                let above = &result[r - 1][col];
-                if let (&High, &High) | (&Low, &Low) = (&elev, above) {
-                    result[r - 1][col] = Mid;
                 }
             }
-            scanned_row.push(elev);
-        }
-        result.push(scanned_row);
-    }
-    result
-}
 
-
-fn part1(map: &[Vec<u32>], compares: &[Vec<Elevation>]) -> u32 {
-    let mut result = 0;
-    for (r, row) in compares.iter().enumerate() {
-        for (col, elev) in row.iter().enumerate() {
-            if let Low = elev {
-                result += map[r][col] + 1
+            if r > 0 {
+                if map[r][col].height <= map[r - 1][col].height {
+                    map[r - 1][col].min = false;
+                    if map[r][col].height == map[r - 1][col].height {
+                        map[r][col].min = false;
+                    }
+                }
             }
         }
     }
-    result
+
+    // for (r, row) in map.rows().enumerate() {
+    //     for (col, cell) in row.iter().enumerate() {
+    //         if col > 0 && cell.height < row[col - 1].height {
+    //             map[r][col - 1].min = false;
+    //         }
+
+    //         if r > 0 && cell.height < map[r - 1][col].height {
+    //             map[r - 1][col].min = false;
+    //         }
+    //     }
+    // }
+}
+
+
+fn part1(map: &Vec2<Cell>) -> u32 {
+    map.values()
+        .filter(|c| c.min)
+        .fold(0, |acc, c| acc + c.height + 1)
 }
 
 
 pub fn run(data: &str) -> eyre::Result<(u32, u32)> {
-    let map = load(data)?;
-    let compares = scan(&map);
+    let sample = "2199943210\n3987894921\n9856789892\n8767896789\n9899965678";
+    let mut map = load(sample)?;
+    scan(&mut map);
 
-    let one = part1(&map, &compares);
+    dbg!(&map[1], &map[2]);
+
+    for (i, cell) in map.values().enumerate() {
+        if cell.min {
+            println!("{}, {} ({})", i / map.row_count(), i % map.row_count(), cell.height)
+        }
+    }
+
+    let one = part1(&map);
     Ok((one, 0))
 }
diff --git a/2021/src/lib.rs b/2021/src/lib.rs
index 8b658ce..341c2c2 100644
--- a/2021/src/lib.rs
+++ b/2021/src/lib.rs
@@ -80,25 +80,31 @@ pub struct Vec2<T> {
 
 
 impl<T> Vec2<T> {
-    fn new(columns: usize) -> Vec2<T> {
+    pub fn new(columns: usize) -> Vec2<T> {
         Vec2 {data: Vec::<T>::new(), columns}
     }
 
-    fn push<S: IntoIterator<Item=T>>(&mut self, row: S) {
+    pub fn push<S: IntoIterator<Item=T>>(&mut self, row: S) {
         self.data.extend(row.into_iter());
     }
-    
-    // This works just fine, for some reason
-    fn rows(&self) -> impl Iterator<Item=&[T]> {
+
+    pub fn row_count(&self) -> usize {
+        self.data.len() / self.columns
+    }
+
+    pub fn col_count(&self) -> usize {
+        self.columns
+    }
+
+    pub fn rows(&self) -> impl Iterator<Item=&[T]> {
         self.data.chunks_exact(self.columns)
     }
 
-    // But this doesn't? 
-    fn rows_mut(&mut self) -> impl Iterator<Item=&mut [T]> {
+    pub fn rows_mut(&mut self) -> impl Iterator<Item=&mut [T]> {
         self.data.chunks_exact_mut(self.columns)
     }
     
-    fn values(&self) -> impl Iterator<Item=&T> {
+    pub fn values(&self) -> impl Iterator<Item=&T> {
         self.data.iter()
     }
 }