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） Typical tests and adjustment of salinity amounts are very important for your very well-being of one's maritime everyday living. Usually use a reputable hydrometer or refractometer to evaluate salinity properly. ... https://pearlaquatics.my/why-hiring-a-professional-aquarium-or-pond-cleaning-service-is-important/