README.md

374. 猜数字大小

English Version

题目描述

猜数字游戏的规则如下：

• 每轮游戏，我都会从 1 到 n 随机选择一个数字。 请你猜选出的是哪个数字。
• 如果你猜错了，我会告诉你，你猜测的数字比我选出的数字是大了还是小了。

你可以通过调用一个预先定义好的接口 int guess(int num) 来获取猜测结果，返回值一共有 3 种可能的情况（-1，1 或 0）：

• -1：我选出的数字比你猜的数字小 pick < num
• 1：我选出的数字比你猜的数字大 pick > num
• 0：我选出的数字和你猜的数字一样。恭喜！你猜对了！pick == num

返回我选出的数字。

 

示例 1：

输入：n = 10, pick = 6
输出：6

示例 2：

输入：n = 1, pick = 1
输出：1

示例 3：

输入：n = 2, pick = 1
输出：1

示例 4：

输入：n = 2, pick = 2
输出：2

 

提示：

• 1 <= n <= 231 - 1
• 1 <= pick <= n

解法

Python3

# The guess API is already defined for you.
# @param num, your guess
# @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
# def guess(num: int) -> int:

class Solution:
    def guessNumber(self, n: int) -> int:
        left, right = 1, n
        while left < right:
            mid = (left + right) >> 1
            if guess(mid) <= 0:
                right = mid
            else:
                left = mid + 1
        return left

Java

/**
 * Forward declaration of guess API.
 * @param  num   your guess
 * @return 	     -1 if num is lower than the guess number
 *			      1 if num is higher than the guess number
 *               otherwise return 0
 * int guess(int num);
 */

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int left = 1, right = n;
        while (left < right) {
            int mid = (left + right) >>> 1;
            if (guess(mid) <= 0) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }
        return left;
    }
}

C++

/**
 * Forward declaration of guess API.
 * @param  num   your guess
 * @return 	     -1 if num is lower than the guess number
 *			      1 if num is higher than the guess number
 *               otherwise return 0
 * int guess(int num);
 */

class Solution {
public:
    int guessNumber(int n) {
        int left = 1, right = n;
        while (left < right) {
            int mid = left + ((right - left) >> 1);
            if (guess(mid) <= 0) {
                right = mid;
            } else {
                left = mid + 1;
            }
        }
        return left;
    }
};

Go

/**
 * Forward declaration of guess API.
 * @param  num   your guess
 * @return 	     -1 if num is lower than the guess number
 *			      1 if num is higher than the guess number
 *               otherwise return 0
 * func guess(num int) int;
 */

func guessNumber(n int) int {
	left, right := 1, n
	for left < right {
		mid := (left + right) >> 1
		if guess(mid) <= 0 {
			right = mid
		} else {
			left = mid + 1
		}
	}
	return left
}

C#

/**
 * Forward declaration of guess API.
 * @param  num   your guess
 * @return 	     -1 if num is lower than the guess number
 *			      1 if num is higher than the guess number
 *               otherwise return 0
 * int guess(int num);
 */

public class Solution : GuessGame {
    public int GuessNumber(int n) {
        int left = 1, right = n;
        while (left < right)
        {
            int mid = left + ((right - left) >> 1);
            if (guess(mid) <= 0)
            {
                right = mid;
            }
            else
            {
                left = mid + 1;
            }
        }
        return left;
    }
}

...