再用n2的时间（两重循环）枚举d-c，并将b-c的值作为键，在Hash数组中查找是否存在。如果能找到critical相同的node点，则找到了一组满足 d-c = a+b的值。（注意检查a b c d 四个数不重复） Regular testing and adjustment of salinity concentrations are very important for the well-being of your marine life. Constantly use a reputable hydrometer or refractometer to evaluate salinity correctly. 三個月 ... https://pearlaquatics.my/routine-maintenance/