摘要：高斯消元 首先想到状压搜索,但是会T 然后我们考虑到一个开关的最后状态,与它的开始状态与所有与它有关操作的异或和有关 因为每个开关只能操作一次,我们可以把每个开关看作是一个元,这些元之间用异或关系连接起来 cpp include include include include include inc 阅读全文

摘要：高斯消元 注意浮点误差,判断一个浮点数是否为 0 的时候,看他的绝对值与 $10^{ 8}$的关系 cpp include include include include include include using namespace std; double a[20][20], b[20], c[ 阅读全文