12只球中挑坏球

12个球中选坏球： 有12个球，其中有一个是坏球，坏球的重量比其它球或轻或重，但不知道是轻还是重。
有一架天平，只准称三次，找出坏球，并说出坏球比好球是轻还是重。

 

 

package yzg.arithmetic;

import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;

/**
 * 12个球中选坏球： 有12个球，其中有一个是坏球，坏球的重量比其它球或轻或重，但不知道是轻还是重。
 * 有一架天平，只准称三次，找出坏球，并说出比好球是轻还是重。
 *
 * @author yzg
 *
 */
public class SelectBadBall {
    int s; // 键盘输入的值
    int t1; // 第一次称的结果
    int t2; // 第二次称的结果
    int t3; // 第三次称的结果
    int h; // 坏球号码
    int p; // 坏球是重还是轻，1：轻 0：重
    int x1, x2, x3, x4; // 
    int r; // 

    String[] q = { "左重", "平衡", "右重" };

    /**
     * @param args
     */
    public static void main(String[] args) {
        SelectBadBall sbb = new SelectBadBall();
        sbb.execute();
    }

    public void execute() {
        System.out.println("计算机判断12只球中的坏球问题");
        System.out.println("请你认定坏球的球号(1~12之一)，并想好它是轻的或是重的！");
        System.out.println("称三次，请你回答三个问题（天平状态）。");
        System.out.println("则计算机可以推算出你认定的坏球号和轻重！");
        System.out.println("开始称球......");
        System.out.println("第一次称：1~4号球放在天平左端，5~8号球放在天平右端。");

        t1 = p3();
        p = t1;
        if (t1 == 1) {
            System.out.println("说明1~8号球是好的，坏球在9~12号球当中。");
            System.out.println("第二次称：9、10号球放在天平左端；11、1号（显然是好球）放在右端。");
            x1 = 9;
            x2 = 10;
            x3 = 11;
            x4 = 12;
            r = 1;

            t2 = p3();
            if (t2 == 1) {
                System.out.println("第三次称：" + x4 + "号球放左端，" + r + "号球放右端。");
                t3 = p2();
                h = x4;
                if (t3 == 0) {
                    p = 1;
                } else {
                    p = 0;
                }
            } else {
                w3(x1, x2, x3);
            }
        } else {
            System.out.println("可推出9~12号球是好的，坏球在1~8号当中。");
            System.out.println("第二次称：左端1、2号球不动，拿走3号球，4号球与右端5号球交换，右端6号球不动，");
            System.out.println("拿走7、8号球，补放12号球（好球）。");

            t2 = p3();
            r = 12;
            if (t1 + t2 == 2) {
                System.out.println("第三次称：4号球放在天平左端，12号球放在右端。");
                t3 = p3();
                h = 4;
                if (t3 == 0) {
                    p = 1;
                } else if (t3 == 2) {
                    h = 5;
                    if (t2 == 0) {
                        p = 1;
                    } else {
                        p = 0;
                    }
                }
            } else {
                if (t1 == 0 && t2 == 0 || t1 == 2 && t2 == 2) {
                    x1 = 1;
                    x2 = 2;
                    x3 = 6;
                } else {
                    x1 = 7;
                    x2 = 8;
                    x3 = 3;
                    if (t1 == 0) {
                        t2 = 2;
                    } else {
                        t2 = 0;
                    }
                }
                w3(x1, x2, x3);
            }
        }
        System.out.println("最后推出坏球是" + h + "号，");
        if (p == 0) {
            System.out.println("是轻的！！");
        } else {
            System.out.println("是重的！！");
        }
    }

    /**
     * 两种答案选择函数（一坏球一好球）
     */
    public int p2() {
        System.out.println("请回答这时天平的状态（0：左重 2：右重）：");
        s = getCh();
        if (s == 0 || s == 2) {
            System.out.println("你选择了:" + q[s]);
        } else {
            System.out.println("你选择错误！请重新选择！");
            s = p2();
        }
        return s;
    }

    /**
     * 三种答案选择函数
     *
     * @return
     */
    public int p3() {
        System.out.println("请回答这时天平的状态（0：左重 1：平衡 2：右重）：");
        s = getCh();
        if (s == 0 || s == 1 || s == 2) {
            System.out.println("你选择了:" + q[s]);
        } else {
            System.out.println("你选择错误！请重新选择！");
            s = p3();
        }
        return s;
    }

    /**
     * 称三球后，称两球判断函数。
     *
     * @param x1
     * @param x2
     * @param x3
     */
    public void w3(int x1, int x2, int x3) {
        System.out.println("可推出坏球在" + x1 + "号、" + x2 + "号和" + x3 + "号之中。");
        System.out.println("第三次称：" + x1 + "放在天平左端，" + x2 + "号球放在右端。");
        t3 = p3();
        if (t3 == 1) {
            h = x3;

            if (t2 == 0) {
                p = 0;
            } else {
                p = 1;
            }
        } else if (t2 == 0 && t3 == 0) {
            h = x1;
            p = 1;
        } else if (t2 == 0 && t3 == 2) {
            h = x2;
            p = 1;
        } else if (t2 == 2 && t3 == 0) {
            h = x2;
            p = 0;
        } else {
            h = x1;
            p = 0;
        }
    }

    /**
     * 接收键盘的输入
     *
     * @return 输入的数字
     */
    public int getCh() {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
        int ret = -1;
        try {
            ret = Integer.parseInt(br.readLine());
        } catch (NumberFormatException e) {
            // e.printStackTrace();
        } catch (IOException e) {
            // e.printStackTrace();
        }
        return ret;
    }
}