leetcode 374. Guess Number Higher or Lower 猜数游戏 + 二分查找

墨蓝 2022-06-07 02:47 155阅读 0赞

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.

最经典的猜数游戏。

代码如下：

/* 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 beg=1 , end=n;
            while(beg<end)
            {
                int mid=(end-beg)/2 + beg;
                int res=guess(mid);
                if(res==0)
                    return mid;
                else if(res==1)
                    beg=mid+1;
                else 
                    end=mid-1;
            }
    
            return beg;
        }
    }

下面是C++的做法，

就是一个简单的二分查找

代码如下：

#include <iostream>
    #include <vector>
    #include <map>
    #include <unordered_map>
    #include <set>
    #include <unordered_set>
    #include <queue>
    #include <stack>
    #include <string>
    #include <climits>
    #include <algorithm>
    #include <sstream>
    #include <functional>
    #include <bitset>
    #include <numeric>
    #include <cmath>
    #include <regex>
    
    using namespace std;
    
    // 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 beg = 1, end = n;
            while (beg < end)
            {
                int mid = (end - beg) / 2 + beg;
                int res = guess(mid);
                if (res == 0)
                    return mid;
                else if (res == 1)
                    beg = mid + 1;
                else if(res==-1)
                    end = mid - 1;
            }
            return beg;
        }
    };