leetcode 374. Guess Number Higher or Lower 猜数游戏 + 二分查找-蒲公英云

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

墨蓝 2022-06-07 02:47 228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;
    }
};