problem_194.js

// This problem was asked by Facebook.
//
// Suppose you are given two lists of n points, one list p1, p2, ..., pn on the
// line y = 0 and the other list q1, q2, ..., qn on the line y = 1. Imagine a
// set of n line segments connecting each point pi to qi. Write an algorithm to
// determine how many pairs of the line segments intersect.