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essential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） All trademarks are both the residence of Central Backyard garden & Pet Corporation, its subsidiaries, divisions, affiliated and/or associated corporations or maybe the residence in their respective owners. Anyth... https://pearlaquatics.my/product/aquadene-general-cure/