一个可以找到并发事件的算法。程序运用了闭包搜寻矩阵的算法。-It is important in distributed computer systems to identify

those events (at identifiable points in time) that are concurrent, or

not related to each other in time. A group of concurrent events may

sometimes attempt to simultaneously use the same resource, and this

could cause problems.

In this problem you will be supplied with lists of sequential events

for an arbitrary number of computations, and the identification of an

arbitrary number of messages sent between these computations. Let n

be the number of events. Your task is to write an O(n3) program to

find out how many pairs of events are concurrent