阿里2017年3月線上程式設計題

package yuyin.chuli;

import java.math.BigDecimal;
import java.util.Scanner;

public class Main {

    /** 請完成下面這個函式，實現題目要求的功能 **/
    /** 當然，你也可以不按照這個模板來作答，完全按照自己的想法來 ^-^ **/
    static double leartCurve(double mu1, double sigma1, double mu2,
            double sigma2) {
        double
 
 x;
        double y;
        int n = 0;
        double re = 0.0;
        double tmp;
        for (int i = 0; i <= 10000; i++) {
            x = normalRandom(mu1, sigma1);
            System.out.println(x);
            y = normalRandom(mu2, sigma2);
            tmp = Math.pow(Math.pow(x, 2) + Math.pow(y, 2
 
) - 1, 2)
                    - Math.pow(x, 2) * Math.pow(y, 2);
            if (tmp > 0) {
                n++;
            }
        }
        re = n / 10000.0;
        BigDecimal bd = new BigDecimal(re);
        bd = bd.setScale(1, BigDecimal.ROUND_HALF_UP);
        return Double.parseDouble(bd.toString());
    }

    public
 
 static double normalRandom(double a, double b) {
        double f = 0;
        double c0 = 2.515517, c1 = 0.802853, c2 = 0.010328;
        double d1 = 1.432788, d2 = 0.189269, d3 = 0.001308;
        double w;
        double r = Math.random();
        if (r <= 0.5)
            w = r;
        else
            w = 1 - r;
        if ((r - 0.5) > 0)
            f = 1;
        else if ((r - 0.5) < 0)
            f = -1;
        double y = Math.sqrt((-2) * Math.log(w));
        double x = f
                * (y - (c0 + c1 * y + c2 * y * y)
                        / (1 + d1 * y + d2 * y * y + d3 * y * y * y));
        double z = a + x * Math.sqrt(b);
        return (z);
    }

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        double res;

        double _mu1;
        _mu1 = Double.parseDouble(in.nextLine().trim());

        double _sigma1;
        _sigma1 = Double.parseDouble(in.nextLine().trim());

        double _mu2;
        _mu2 = Double.parseDouble(in.nextLine().trim());

        double _sigma2;
        _sigma2 = Double.parseDouble(in.nextLine().trim());

        res = leartCurve(_mu1, _sigma1, _mu2, _sigma2);
        System.out.println(String.valueOf(res));
    }
}

程式設計題

package yuyin.test;

import java.util.HashMap;
import java.util.Random;
import java.util.Scanner;
//n個相親名單，每次隨機一個，已經約過的丟失，繼續隨機約，求平均多少次才能面完所有姑娘
public class M01 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        //總次數
        double all_result=0;
        //每次的次數
        int result=0;
        //每次相親多少個
        int n= Integer.parseInt(in.nextLine().trim());
        for (int i = 0; i < 10000; i++) {
            result=One(n);
            all_result+=result;
        }
        //平均次數
        double avg=all_result/10000 ;
        System.out.println(avg);
    }

    private static int One(int n) {
        if (n==1) {
            return 1;
        }
        //初始n個姑娘
        //已經約會過的女孩
        Random rand = new Random();
        int old = rand.nextInt(n); 
        //開始約會  //未約會列表
        HashMap<Integer, Integer> m=new HashMap<Integer, Integer>();
        for (int i = old+1; i < n; i++) {
            m.put(i, 1);
        }
        int count=0;
        while (m.size()>0) {
            int start = rand.nextInt(n); 
            if (start>old) {
                m.remove(start);
            }
            count+=1;
        }
//      System.out.println(count);
        return count;
    }
}