欧拉工程第71题：Ordered fractions

 

题目链接：https://projecteuler.net/problem=71

 If n<d and HCF(n,d)=1, it is called a reduced proper fraction.

 

n/d 真分数升序排序后，离 3/7最近的数，d<=1000000

 

Java程序：

public class P71{
    void run(){
        calculate();
    }
    void calculate(){
        int max_n = 1000000;
        long a = 3;
        long b = 7;
        long r = 0;
        long s = 1;
        int q = 0;
        long p = 0;
        for( q = max_n;q>2;q--){
             p = (a*q-1)/b;
            if(p*s>r*q){
                s = q;
                r = p;
            }
        }
        System.out.println(r+"/"+s);
    }


    public static void main(String[] args){
        long t0 = System.currentTimeMillis();
        new P71().run();
        long t1= System.currentTimeMillis();
        System.out.println((t1-t0)+"ms");
    }
}