LeetCode 374 猜数字大小[二分法] HERODING的LeetCode之路

Posted 2021-06-27 HERODING23

解题思路：
一道简单题温习一遍二分的知识，和一般的二分法不同，通常的二分法会使low与high逼近一个相邻的数，然后返回low或者high，这一般是求临界值，而本题不同，只要是满足条件返回即可，代码如下：

/** 
 * 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) {
        long long low = 1, high = n;
        int mid;
        while(1) {
            // 中间值
            mid = (low + high) / 2;
            if(guess(mid) == 0) {
                break;
            }else if(guess(mid) == -1) {
                high = mid;
            } else {
                low = mid + 1;
            }
        }
        return mid;
    }
};


/*作者：heroding
链接：https://leetcode-cn.com/problems/guess-number-higher-or-lower/solution/cer-fen-fa-by-heroding-hss4/
来源：力扣（LeetCode）
著作权归作者所有。商业转载请联系作者获得授权，非商业转载请注明出处。*/