順番に試す。
class RotatedClock { public: string getEarliest(int H, int M) { for (int i = 0; i < (int)360; i += 30) { int h = (360 + H - i) % 360; int m = (360 + M - i) % 360; int a = h % 30; if (m == a * 12) { char buff[100]; sprintf(buff, "%02d:%02d", h / 30, m / 6); return string(buff); } } return ""; } };