day24 part1

1 files changed, 91 insertions, 0 deletions

diff --git a/2023/day24.rs b/2023/day24.rs
new file mode 100644
index 0000000..69f0b74
--- /dev/null
+++ b/2023/day24.rs
@@ -0,0 +1,91 @@
+#![allow(dead_code)]
+#![allow(unused_variables)]
+#![allow(unused_mut)]
+use std::env;
+use std::fs::File;
+use std::io::Read;
+
+#[derive(Debug)]
+struct Stone {
+    x: Vec<f64>,
+    v: Vec<f64>,
+}
+
+fn ints(s: &str) -> Vec<f64> {
+    s.to_string()
+        .split(|c: char| !c.is_numeric() && c != '-')
+        .filter_map(|x| x.parse().ok())
+        .collect()
+}
+
+fn crosses_xy(s1: &Stone, s2: &Stone, coord_min: f64, coord_max: f64) -> bool {
+    // y = y0 + yv * (x - x0) / xv
+    let n1: f64 = s1.x[1] - s1.x[0] * s1.v[1] / s1.v[0];
+    let k1: f64 = s1.v[1] / s1.v[0];
+
+    let n2: f64 = s2.x[1] - s2.x[0] * s2.v[1] / s2.v[0];
+    let k2: f64 = s2.v[1] / s2.v[0];
+
+    if k1 == k2 {
+        return false;
+    }
+
+    let x = (n2 - n1) / (k1 - k2);
+    let y = x * k1 + n1;
+
+    let t1 = (x - s1.x[0]) / s1.v[0];
+    let t2 = (x - s2.x[0]) / s2.v[0];
+
+    if (coord_min <= x)
+        && (x <= coord_max)
+        && (coord_min <= y)
+        && (y <= coord_max)
+        && (t1 >= 0.)
+        && (t2 >= 0.)
+    {
+        return true;
+    }
+
+    false
+}
+
+fn main() {
+    let args: Vec<String> = env::args().collect();
+    let filename = if args.len() == 1 {
+        "in/".to_owned() + args[0].split('/').last().unwrap() + ".pzl"
+    } else {
+        args[1].clone()
+    };
+    let mut f = File::open(filename).expect("cannot open file");
+    let mut content = String::new();
+    f.read_to_string(&mut content).expect("cannot read file");
+    let lines = content.trim_end().split("\n");
+
+    let mut ss: Vec<Stone> = Vec::new();
+    for line in lines {
+        let (x, v) = line.split_once("@").unwrap();
+        ss.push(Stone {
+            x: ints(x),
+            v: ints(v),
+        });
+    }
+
+    let coord_min = 200000000000000.0;
+    let coord_max = 400000000000000.0;
+    // let coord_min = 7.0;
+    // let coord_max = 27.0;
+
+    let mut cross: Vec<bool> = Vec::new();
+    for i in 0..ss.len() {
+        for j in i..ss.len() {
+            cross.push(crosses_xy(&ss[i], &ss[j], coord_min, coord_max));
+        }
+    }
+
+    let res1 = cross.iter().filter(|x| **x).fold(0, |x, _| x + 1);
+
+    let mut res2 = 0;
+
+    println!("res1: {}", res1);
+    println!("res2: {}", res2);
+}