Find-Smallest-Letter-Greater-Than-Target.cpp

class Solution
{
  public:
    char nextGreatestLetter(vector<char> &letters, char target)
    {
        int n = letters.size(), l = 0, r = n - 1, mid;
        while (l <= r)
        {
            mid = (l + r) >> 1;
            if (letters[mid] > target)
            {
                r = mid - 1;
            }
            else
                l = mid + 1;
        };
        return letters[l % n];
    }
};