// 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 l = 1, r = n; 
        while (l < r){
            int m = l + (r - l) / 2;
            int res = guess(m);
            //cout << res << endl;
            if (res == 0){
                return m;
            }
            else if (res == 1){
                l = m + 1;
            }
            else if (res == -1){
                r = m - 1;
            }
        }
        return l;
    }
};

这是leetcode上的一道二分题目，请问一下 int m = l + (r - l) / 2;与 int m = (l + r) >> 1区别在哪里哦？为什么我用后者直接超时了，前者过了。为什么前者更快啊，后者不是位运算吗