几个STL算法:includes,set_difference、set_intersection、set_symmetric_difference、set_union, pre_permutation,
includes:测试有序序列中是否包含另一个序列的全部元素。templateboolincludes(inputIterator1first1,inputIterator1last1, inputIterator2first2,inputIterator2last2);templateboolincludes(inputIterator1first1,inp