摘要："C 2D Plane 2N Points" 题意 二维平面上有$N$个红点，$N$个蓝点，一个红点和一个蓝点能配成一对当且仅当$x_r define F(i, a, b) for (int i = (a); i (b); i) define dF2(i, a, b) for (int i = (a 阅读全文