374. Guess the size of numbers (must be able to get started)

Problem description ：

374. Guess the size of the numbers

The rules of the number guessing game are as follows ：

    Every round of the game , I'll start from 1 To n Randomly choose a number . Please guess which number is chosen .
    If you guessed wrong , I'll tell you , Is your guess larger or smaller than the number I selected .

You can call a predefined interface int guess(int num) To get a guess , The total number of return values is 3 A possible situation （-1,1 or 0）：

    -1： The number I picked is smaller than your guess pick < num
    1： The number I picked was bigger than you guessed pick > num
    0： I picked the same number as you guessed . Congratulations ！ You guessed it ！pick == num

Back to the number I picked .

Example ：

Example 1：

Input ：n = 10, pick = 6
Output ：6

Example 2：

Input ：n = 1, pick = 1
Output ：1

Example 3：

Input ：n = 2, pick = 1
Output ：1

Example 4：

Input ：n = 2, pick = 2
Output ：2

Tips ：

    1 <= n <= 231 - 1
    1 <= pick <= n

Take the code and run it ：

package com.onlyqi.test03.erfen;

import java.util.Scanner;

/**
 * @author
 * @date 2022/7/11 18:55
 * @description
 */
public class Test02 {
    public static void main(String[] args) {
        Scanner scan=new Scanner(System.in);       //scanner Instantiation 
        System.out.println(" Please enter what you want to enter n:");
        int a=scan.nextInt();
        System.out.println("====================="+guessNumber(a));
    }
    public static int guessNumber(int n) {
        int low = 1;
        int high = n;
        while (low <= high) {
            int mid = low + (high - low) / 2;
            int res = guess(mid);
            if (res == 0)
                return mid;
            else if (res < 0)
                high = mid - 1;
            else
                low = mid + 1;
        }
        return -1;
    }

    public static int guess(int num){
        int pick=66;
        if(pick>num){
            return 1;
        }else if(pick<num){
            return -1;
        }else {
            return 0;
        }
    }
}

Running results ：

I want to brush it 300 Algorithm questions , The first 103 Avenue