说明：  给出你设计的求解下面问题算法的伪代码并分析复杂性：设B={b1,b2, ,bn} 和 W={w1,w2, ,wn}为平面上黑点和白点的两个集合。一个黑点bi=(xi, yi )与一个白点wj=(xj, yj ) 匹配当且仅当xi≥xj 和yi≥yj 。设计一个贪心算法，找出黑白点之间的最大匹配数目。算法的复杂性要尽量接近nlgn.
(Give your algorithm designed to solve the following pseudo code and the problem of complexity: Let B = {b1, b2,, bn} and W = {w1, w2,, wn} is flat black spots and white spots on the two collection. A black dot bi = (xi, yi) with a white wj = (xj, yj) match if and only if xi ≥ xj and yi ≥ yj. Design a greedy algorithm to find the maximum match between black and white point number. Complexity of the algorithm to be as close as possible nlgn.)