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vital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） Live plants are more than simply decorative elements within a freshwater aquarium. They add to oxygenation, enable preserve water good quality, and supply pure habitats for fish. अन्‍य डेटा गोपनीयता संबंधी तौर-तरीक़... https://pearlaquatics.my/how-is-an-aquarium-set-up/