牛肉豚肉合いびき肉計算機初版

ideal_mixed_ground_meat_calclator.rs

#[derive(Clone)]
struct RatioBuilder{
    n:i64,
    a_name:Option<String>,
    a_ratio:Option<i64>,
    b_name:Option<String>,
    b_ratio:Option<i64>,
}

impl RatioBuilder{
    fn new(n:i64)->Self{
        RatioBuilder{
            n:n,
            a_name:None,
            a_ratio:None,
            b_name:None,
            b_ratio:None
        }
    }
    fn set_corr(&mut self,a_name:&str,b_name:&str,a_ratio:i64,b_ratio:i64)->Self{
        let mut s = self.clone();
        s.a_name = Some(a_name.to_owned());
        s.a_ratio = Some(a_ratio);
        s.b_name = Some(b_name.to_owned());
        s.b_ratio = Some(b_ratio);
        s
    }
    fn build(&self)->Option<Ratio>{
        if self.a_name == None || self.a_ratio == None ||
            self.b_name == None || self.b_ratio == None{
            return None;
        }
        Some(
            Ratio{
                n:self.n,
                a_name:self.a_name.clone().unwrap(),
                a_ratio:self.a_ratio.unwrap(),
                b_name:self.b_name.clone().unwrap(),
                b_ratio:self.b_ratio.unwrap()
            }
        )
    }
}

#[derive(Clone)]
struct Ratio{
    n:i64,
    a_name:String,
    a_ratio:i64,
    b_name:String,
    b_ratio:i64,
}
impl Ratio{
    fn calc_impl(&self,p:i64,q:i64)->(i64,String){
        let a = self.a_ratio;
        let b = self.b_ratio;
        let n = self.n;
        let x = b*n/(a+b);
        // 比率の比較
        if b*1000/a < q*1000/p{
            // 豚肉を増やす。
            (q*(n-x)/p-x,self.b_name.clone())
        }else {
            // 牛肉を増やす。
            (p*x/q-(n-x),self.a_name.clone())
        }
    }

    fn calculate(&self,a_new:i64,b_new:i64)->(Self,i64,String){
        let (ans,name) = self.calc_impl(a_new,b_new);
        let mut s = self.clone();
        s.a_ratio = a_new;
        s.b_ratio = b_new;
        (s,ans,name)
    }
    fn get_ratio_string(&self)->String{
        format!("{} : {}",self.a_ratio,self.b_ratio)
    }
}

fn main() {
    let r = RatioBuilder::new(150).set_corr("牛肉", "豚肉", 7,3).build().unwrap();

    let array = [
        r.calculate(1,1), r.calculate(2,1),r.calculate(3,1),r.calculate(4,1)
        ,r.calculate(5,1),r.calculate(7,3),r.calculate(1,2),r.calculate(1,3)
        ,r.calculate(1,4),r.calculate(1,5),r.calculate(3,7)
    ];
    for (ratio_object,ans,name) in array.iter(){
        if *ans != 0{
            println!("既知の比率({})から、新しい比率({})にするには {} を {} g 追加",r.get_ratio_string(),ratio_object.get_ratio_string(),name,ans);
        }else{
            println!("追加操作は必要ありません");
        }
    }
    println!("--------");
    let r = RatioBuilder::new(150).set_corr("牛肉", "豚肉", 3,7).build().unwrap();
    let array = [
        r.calculate(1,1), r.calculate(2,1),r.calculate(3,1),r.calculate(4,1)
        ,r.calculate(5,1),r.calculate(7,3),r.calculate(1,2),r.calculate(1,3)
        ,r.calculate(1,4),r.calculate(1,5),r.calculate(3,7)
    ];
    for (ratio_object,ans,name) in array.iter(){
        if *ans != 0{
            println!("既知の比率({})から、新しい比率({})にするには {} を {} g 追加",r.get_ratio_string(),ratio_object.get_ratio_string(),name,ans);
        }else{
            println!("追加操作は必要ありません");
        }
    }
}