package cn.kimtian.array.one;

import java.util.Scanner;

/**
 * 題目：出示一個任意價格的商品（在XXX-XXX元內），參與者要猜這件商品的價格，然後會有人給出相應高了或低了的提示，直到猜出這個價格為止
 * 使用二分法來
 *
 * @author kimtian
 */
public class AlgorithmOne {
    public static void main(String[] args) {
        AlgorithmOne algorithmOne = new AlgorithmOne();
        System.out.println("請輸入商品的價格,注意輸入一個整數哦！");
        Scanner scanner = new Scanner(System.in);
        int price = scanner.nextInt();
        System.out.println("請輸入要猜的價格範圍，以-分割");
        String range = scanner.next();
        String nums[] = range.split("-");
        //校驗分割後的結果只允許為兩個值，否則格式不通過
        if (nums.length != 2) {
            System.out.println("價格範圍輸入錯誤");
        }
        //比較左右兩個值，哪個大哪個為heightPrice，哪個小哪個為lowPrice
        else {
            int num1 = Integer.parseInt(nums[0]);
            int num2 = Integer.parseInt(nums[1]);
            if (num1 > num2) {
                System.out.println(algorithmOne.guessPrice(num2, num1, price));
            } else {
                System.out.println(algorithmOne.guessPrice(num1, num2, price));
            }
        }
    }

    /**
     * 採用二分法
     **/
    public String guessPrice(int lowPrice, int heightPrice, int price) {
        // 判斷是否在範圍中，不在就不執行後面了，避免死迴圈
        if (price > heightPrice || price < lowPrice) {
            return "實物價格不在給定範圍中";
        } else {
            int height = heightPrice;
            int low = lowPrice;
            int guessPrice = (low + heightPrice) / 2;
            //記錄一下執行次數
            int i = 0;
            while (guessPrice != price) {
                // 如果猜大了，那麼最大值就是猜的值
                if (guessPrice > price) {
                    height = guessPrice;
                }
                // 如果猜小了，那麼最小值就是猜的值
                else if (guessPrice < price) {
                    low = guessPrice;
                }
                guessPrice = (low + height) / 2;
                i++;
            }
            return "共猜了" + (i + 1) + "次，猜到了價格是：" + guessPrice + "元。";
        }

    }
}