1 files changed, 41 insertions, 0 deletions
diff --git a/09/src/part-1.rs b/09/src/part-1.rs
new file mode 100644
index 0000000..63d96af
--- /dev/null
+++ b/09/src/part-1.rs
@@ -0,0 +1,41 @@
+mod tensor;
+
+use std::io::{BufRead};
+
+pub type Matrix = tensor::Tensor<usize, 2>;
+pub type Index = tensor::Index<2>;
+
+pub fn main() {
+    let mut stdin = std::io::stdin();
+    let mut handle = stdin.lock();
+
+    let x: Matrix = {
+        let mut tmp: Vec<usize> = Vec::new();
+        let mut m: usize = 0;
+        for l in handle.lines() {
+            let line = l.unwrap();
+            tmp.extend(line.chars().map(|c| c.to_digit(10).unwrap() as usize));
+            m += 1;
+        }
+        let n = tmp.len()/m;
+        Matrix::new_from([m, n], tmp)
+    };
+
+    let mut neighbors: Vec<Option<& usize>> = Vec::new();
+    let mut low_points: Vec<usize> = Vec::new();
+    for i in 0..x.shape()[0] {
+        for j in 0..x.shape()[1] {
+            neighbors.clear();
+            neighbors.push(x.el(& [i, j.wrapping_sub(1)]));
+            neighbors.push(x.el(& [i, j+1]));
+            neighbors.push(x.el(& [i.wrapping_sub(1), j]));
+            neighbors.push(x.el(& [i+1, j]));
+
+            let min_neighbor: usize = (& neighbors).into_iter().filter_map(|& y| y).map(|& y| y).min().unwrap();
+            if min_neighbor > x[[i, j]] { low_points.push(x[[i, j]]); }
+        }
+    }
+
+    let total_risk: usize = low_points.into_iter().map(|l| l+1).sum();
+    println!("Total risk: {}", total_risk);
+}