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crucial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 vegetation tend to be more than just ornamental elements inside of a freshwater aquarium. They lead to oxygenation, assistance maintain water high-quality, and provide normal habitats for fish. ● पोस्ट, स्टोर... https://pearlaquatics.my/how-to-keep-your-aquarium-clean/