374. Guess Number Higher or Lower（python+cpp）

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最新推荐文章于 2024-03-18 09:44:26 发布

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分类专栏： LeetCode

本文链接：https://blog.youkuaiyun.com/qq_21275321/article/details/83622900

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本文介绍了一个猜数字游戏的经典算法解决方案——二分查找法。通过定义的API反馈，逐步缩小猜测范围，直至找到正确答案。文章提供了Python和C++的实现代码，深入解析了二分查找的高效性和应用。

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题目：

We are playing the Guess Game. The game is as follows:
I pick a number from 1 to n. You have to guess which number I picked.
Every time you guess wrong, I’ll tell you whether the number is higher or lower.
You call a pre-defined API guess(int num) which returns 3 possible
results (-1, 1, or 0):
-1 : My number is lower
1 : My number is higher
0 : Congrats! You got it!
Example :
Input: n = 10, pick = 6 
Output: 6

解释：
经典的二分查找的题目。
python代码：

# 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):

class Solution(object):
    def guessNumber(self, n):
        """
        :type n: int
        :rtype: int
        """
        left,right=1,n
        while left<=right:
            mid=left+(right-left)/2
            guessNumber=guess(mid)
            if guessNumber==0:
                return mid
            elif guessNumber>0:
                left=mid+1
            else:
                right=mid-1

c++代码：

// Forward declaration of guess API.
// @param num, your guess
// @return -1 if my number is lower, 1 if my number is higher, 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)/2;
            int guessNumber=guess(mid);
            if (guessNumber==0)
                return mid;
            else if(guessNumber>0)
                left=mid+1;
            else
                right=mid-1;
        }
    }
};

总结：
经典的二分查找问题。