自定义compare 函数

//priority queue 可以用自定义的compare类

struct compare
{
    bool operator()(const int& l, const int& r)
    {
        return l > r;
    }
};

int main(){
　　 priority_queue<int,vector<int>, compare > pq;
    pq.push(2);
    pq.push(3);
    pq.push(3);
    pq.push(1);
    
    while(!pq.empty()){
        cout<<pq.top()<<endl;
        pq.pop();
    }
}

bool myfunction (int i,int j) { return (i<j); }

struct myclass {
  bool operator() (int i,int j) { return (i<j);}
} myobject;

int myints[] = {32,71,12,45,26,80,53,33};
  std::vector<int> myvector (myints, myints+8);               // 32 71 12 45 26 80 53 33

  // using default comparison (operator <):
  std::sort (myvector.begin(), myvector.begin()+4);           //(12 32 45 71)26 80 53 33

  // using function as comp
  std::sort (myvector.begin()+4, myvector.end(), myfunction); // 12 32 45 71(26 33 53 80)

  // using object as comp
  std::sort (myvector.begin(), myvector.end(), myobject);     //(12 26 32 33 45 53 71 80)

 * Definition for an interval.
 * struct Interval {
 *     int start;
 *     int end;
 *     Interval() : start(0), end(0) {}
 *     Interval(int s, int e) : start(s), end(e) {}
 * };

class Solution {
    
public:
    static bool compare (const Interval &a, const Interval &b){
        return a.start<b.start;
    }

    void haha(vector<Interval>& intervals) {
        sort(intervals.begin(), intervals.end(), compare);
    }
};