原题链接:744. 寻找比目标字母大的最小字母
solution: 二分+特判
class Solution {
public:
char nextGreatestLetter(vector<char>& letters, char target) {
int l = 0, r = letters.size();
while(l < r){
int mid = l + r >> 1;
if(letters[mid]>target) r = mid;
else l = mid + 1;
}
if(l == letters.size()) return letters[0];
return letters[l];
}
};