374. Guess Number Higher or Lower

最新推荐文章于 2024-10-21 14:58:17 发布

转载最新推荐文章于 2024-10-21 14:58:17 发布 · 53 阅读

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原文链接：http://www.cnblogs.com/Machelsky/p/5940767.html

本文介绍了一个猜数字游戏的实现算法，使用二分查找法来高效地猜测预先设定的一个1到n之间的数字。通过预定义的API获取反馈，逐步缩小范围直到猜中目标数字。

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:

n = 10, I pick 6.

Return 6.

二分法：最后锁定一个数也就是low=high找到这个数。

/* The guess API is defined in the parent class GuessGame.
   @param num, your guess
   @return -1 if my number is lower, 1 if my number is higher, otherwise return 0
      int guess(int num); */

public class Solution extends GuessGame {
    public int guessNumber(int n) {
        int low=0;
        int high=n;
        
        while(low<high)
        {
            int mid=low+(high-low)/2;
            if(guess(mid)==0)
            {
                return mid;
            }
            else if(guess(mid)==1)
            {
                low=mid+1;
            }
            else
            {
                high=mid-1;
            }
        }
        return low;
        
    }
}

转载于:https://www.cnblogs.com/Machelsky/p/5940767.html