アルゴリズムと数学 036

https://atcoder.jp/contests/math-and-algorithm/tasks/abc168_c

sin/cosはこんな感じですね。

theta.sin()
theta.cos()

// : (Colon)
#![allow(non_snake_case)]

use std::ops::Sub;
use std::f64::consts::PI;


//////////////////// library ////////////////////

fn read<T: std::str::FromStr>() -> T {
    let mut line = String::new();
    std::io::stdin().read_line(&mut line).ok();
    line.trim().parse().ok().unwrap()
}

fn read_vec<T: std::str::FromStr>() -> Vec<T> {
    read::<String>().split_whitespace()
            .map(|e| e.parse().ok().unwrap()).collect()
}


//////////////////// Point ////////////////////

#[derive(Clone, Copy)]
#[derive(Debug)]
struct Point {
    x: f64,
    y: f64,
}

impl Sub for Point {
    type Output = Self;
    
    fn sub(self, other: Self) -> Self {
        Self { x: self.x - other.x, y: self.y - other.y }
    }
}

impl Point {
    fn inner_product(v: &Point, w: &Point) -> f64 {
        v.x * w.x + v.y * w.y
    }
    
    fn mag(&self) -> f64 {
        Point::inner_product(self, self).sqrt()
    }
}


//////////////////// process ////////////////////

fn read_input() -> (i32, i32, i32, i32) {
    let v = read_vec();
    (v[0], v[1], v[2], v[3])
}

fn make_point(L: f64, theta: f64) -> Point {
    Point { x: -L * theta.sin(), y: L * theta.cos() }
}

fn f(A: i32, B: i32, H: i32, M: i32) -> f64 {
    let pt1 = make_point(A as f64, (H as f64 + (M as f64) / 60.0) * PI / 6.0);
    let pt2 = make_point(B as f64, (M as f64) * PI / 30.0);
    (pt1 - pt2).mag()
}

fn main() {
    let (A, B, H, M) = read_input();
    println!("{}", f(A, B, H, M))
}