From bf5747e9925988c8cf053f974fdcc35ca76df361 Mon Sep 17 00:00:00 2001
From: Gard Spreemann <gspr@nonempty.org>
Date: Sun, 11 Dec 2022 16:14:28 +0100
Subject: Days 8 and 9

---
 08/src/part-1.rs | 91 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++
 1 file changed, 91 insertions(+)
 create mode 100644 08/src/part-1.rs

(limited to '08/src/part-1.rs')

diff --git a/08/src/part-1.rs b/08/src/part-1.rs
new file mode 100644
index 0000000..1bbd75a
--- /dev/null
+++ b/08/src/part-1.rs
@@ -0,0 +1,91 @@
+mod tensor;
+
+use std::io::{BufRead};
+
+use tensor::{Index, Shape, Tensor};
+
+fn main() {
+    let stdin = std::io::stdin();
+    let mut handle = stdin.lock();
+
+    let mut tmp: Vec<(i8, bool)> = Vec::new();
+    let mut m: usize = 0;
+    let mut n: usize = 0;
+    let mut n_check: usize = 0;
+    
+    loop {
+        let buf = handle.fill_buf().expect("IO error");
+        let bytes_read = buf.len();
+        if bytes_read == 0 { break; }
+
+        for & b in buf.into_iter() {
+            if b >= b'0' && b <= b'9' {
+                tmp.push(((b - b'0').try_into().unwrap(), false));
+                if m == 0 {
+                    n += 1;
+                }
+                n_check += 1;
+            }
+            if b == b'\n' {
+                m += 1;
+                assert_eq!(n_check, n);
+                n_check = 0;
+            }
+        }
+
+        handle.consume(bytes_read);
+    }
+
+    let mut x: Tensor<(i8, bool), 2> = Tensor::new_from([m, n], tmp);
+    let shape = x.shape().clone();
+    let mut tallest: i8;
+
+    // Look north-south.
+    for j in 0..shape[1] {
+        // Look from north.
+        tallest = -1;
+        for i in 0..shape[0] {
+            let tree = &mut x[[i, j]];
+            if tree.0 > tallest {
+                tree.1 = true;
+                tallest = tree.0;
+            }
+        }
+
+        // Look from south.
+        tallest = -1;
+        for i in (0..shape[0]).rev() {
+            let tree = &mut x[[i, j]];
+            if tree.0 > tallest {
+                tree.1 = true;
+                tallest = tree.0;
+            }
+        }
+    }
+
+    // Look east-west.
+    for i in 0..shape[0] {
+        // Look from west.
+        tallest = -1;
+        for j in 0..shape[1] {
+            let tree = &mut x[[i, j]];
+            if tree.0 > tallest {
+                tree.1 = true;
+                tallest = tree.0;
+            }
+        }
+
+        // Look from east.
+        tallest = -1;
+        for j in (0..shape[1]).rev() {
+            let tree = &mut x[[i, j]];
+            if tree.0 > tallest {
+                tree.1 = true;
+                tallest = tree.0;
+            }
+        }
+    }
+
+    let num_visible = x.data().into_iter().filter(|(_, vis)| *vis).count();
+    println!("{}", num_visible);
+}
-- 
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