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 vegetation tend to be more than just ornamental things in a very freshwater aquarium. They add to oxygenation, help manage drinking water high-quality, and supply natural habitats for fish. 一個月 - 更高级的例... https://pearlaquatics.my/author/jasun/page/3/