Algorithm

• Uses greedy algorithm: want to start with the pair with the smallest tail number (so we can have the most room for the following chain)
• Requires sorting

知识点

• sort c++ vector
  use std::sort(RandomAcessIterator begin, RandomAcessIterator end, Compare comp)
  need to define function for comp

class myClass {
  static bool comp (T a, T b) { //statement }
  void foo() { 
    //statement
    sort(myVector.begin(), myVector.end(), comp);
    //statement
  }
}

or

book comp (T a, T b) { //statement }
class myClass {
  //same
}

需注意在class内define的comp前要加static关键词