day8

2 files changed, 58 insertions, 0 deletions

diff --git a/src/day8.rs b/src/day8.rs
new file mode 100644
index 0000000..e69d5cd
--- /dev/null
+++ b/src/day8.rs
@@ -0,0 +1,56 @@
+fn ss(r: Vec<u32>, t: u32) -> u32 {
+    let mut i: usize = 0;
+    for x in r {
+        if x >= t {
+            i+=1; // If we're blocked, count the blocking tree as visible!
+            break;
+        }
+        i+=1;
+    }
+    i.try_into().unwrap()
+}
+
+// fn visible(r: Vec<u32>, t: u32) -> bool {
+//     r.into_iter().all(|tt| { tt < t })
+// }
+
+pub fn run(input: String) {
+    let grid: Vec<Vec<u32>> = input.lines().map(|line| {
+        line.chars().map(|ch| {
+            ch.to_digit(10).expect("char wasn't a digit!")
+        }).collect()
+    }).collect();
+    let height = grid.len();
+    let width = grid[0].len();
+
+    // Naïve solution, just check every tree's path's to the edge
+    // let visibilities: Vec<Vec<bool>> =
+    let viewingscores: Vec<Vec<u32>> =
+    (0..height).map(|i| {
+        (0..width).map(|j| {
+            if i == 0 || j == 0 || i == height-1 || j == width-1 {
+                // println!("short circuit {} {}",i, j);
+                //return true;
+                return 0;
+            }
+            let t = grid[i][j];
+            let r1: Vec<u32> = (0..i).rev().map(|ii| {grid[ii][j]} ).collect();
+            let r2: Vec<u32> = (i+1..height).map(|ii| {grid[ii][j]} ).collect();
+            let r3: Vec<u32> = (0..j).rev().map(|jj| {grid[i][jj]} ).collect();
+            let r4: Vec<u32> = (j+1..width).map(|jj| {grid[i][jj]}).collect();
+            // let visible = [r1, r2, r3, r4].into_iter().any(|r| {
+            //     visible(r, t)
+            // });
+            // visible
+            // Always see at least 1 tree in any direction
+            [r1, r2, r3, r4].into_iter().map(|r| { ss(r, t) } ).product()
+        }).collect()
+    }).collect();
+    // println!("{:?}", grid);
+    // println!("{:?}", visibilities);
+
+    // let nvisible: u32 = visibilities.into_iter().flatten().into_iter().map(|b| {if b {1} else {0}}).sum();
+    // println!("Day 8: {}", nvisible);
+    let maxvs = viewingscores.into_iter().flatten().max().unwrap();
+    println!("Day 8: {}", maxvs);
+}
\ No newline at end of file
diff --git a/src/main.rs b/src/main.rs
index b370693..5a7634b 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -7,6 +7,7 @@ mod day4;
 mod day5;
 mod day6;
 mod day7;
+mod day8;
 
 fn main() {
     day1::run(fs::read_to_string("input/day1.txt").expect("Failed to read input file!"));
@@ -16,4 +17,5 @@ fn main() {
     day5::run(fs::read_to_string("input/day5.txt").expect("Failed to read input file!"));
     day6::run(fs::read_to_string("input/day6.txt").expect("Failed to read input file!"));
     day7::run(fs::read_to_string("input/day7.txt").expect("Failed to read input file!"));
+    day8::run(fs::read_to_string("input/day8.txt").expect("Failed to read input file!"));
 }