init

problems/p102/src/main.rs

@@ -0,0 +1,91 @@
+use rayon::prelude::*;
+use std::{
+    fs::File,
+    io::{BufRead, BufReader},
+};
+
+struct Point {
+    x: i32,
+    y: i32,
+}
+
+impl Point {
+    fn cross_product(&self, b: &Point, c: &Point) -> i32 {
+        (b.x - self.x) * (c.y - self.y) - (b.y - self.y) * (c.x - self.x)
+    }
+}
+
+struct Triangle {
+    a: Point,
+    b: Point,
+    c: Point,
+}
+
+fn load_triangle() -> Vec<Triangle> {
+    let mut tris = Vec::new();
+    let file = File::open("./problems/p102/p102_triangles.txt").unwrap();
+    let reader = BufReader::new(file);
+
+    let lines: Vec<String> = reader.lines().map(|s| s.unwrap()).collect();
+    for line in lines {
+        // "-340,495,-153,-910,835,-947",
+        let values: Vec<&str> = line.split(',').collect();
+        let values: Vec<i32> = values.iter().map(|&x| x.parse::<i32>().unwrap()).collect();
+
+        let triangle = Triangle {
+            a: Point {
+                x: values[0],
+                y: values[1],
+            },
+            b: Point {
+                x: values[2],
+                y: values[3],
+            },
+            c: Point {
+                x: values[4],
+                y: values[5],
+            },
+        };
+        tris.push(triangle);
+    }
+
+    tris
+}
+
+fn is_include_origin(tri: &Triangle) -> bool {
+    let a = &tri.a;
+    let b = &tri.b;
+    let c = &tri.c;
+    let origin = Point { x: 0, y: 0 };
+    // 对于两个向量 u = (u.x, u.y) 和 v = (v.x, v.y)：
+    // 叉积 = u.x * v.y - u.y * v.x
+
+    let ab_ao = a.cross_product(b, &origin);
+    let bc_bo = b.cross_product(c, &origin);
+    let ca_co = c.cross_product(a, &origin);
+    if ab_ao == 0 || bc_bo == 0 || ca_co == 0 {
+        return true;
+    }
+    matches!(
+        (ab_ao > 0, bc_bo > 0, ca_co > 0),
+        (true, true, true) | (false, false, false)
+    )
+}
+#[test]
+fn test_is_include_origin() {
+    let a = Triangle {
+        a: Point { x: -340, y: 495 },
+        b: Point { x: -153, y: -910 },
+        c: Point { x: 835, y: -947 },
+    };
+    assert!(is_include_origin(&a));
+}
+
+fn main() {
+    let tris = load_triangle();
+    let count = tris
+        .par_iter()
+        .filter(|&tri| is_include_origin(tri))
+        .count();
+    println!("{count}");
+}