topcoder SRM 623 DIV2 CatchTheBeatEasy

比较简单的一题，纠结比较久的是把my_cmp和my_minus放在类中，利用sort函数会出现

no matching function for call to ""sort（std::vector<Interval>::iterator， std::vector<Interval>::iterator， <unresolved overloaded function type>）""

当把这两个函数放在类外面时就行了

#include <iostream>
#include <vector>
#include <utility>
#include <algorithm>
#include <cmath>
#include <numeric>
using namespace std;

typedef pair<int,int> Point;
bool my_cmp(const Point& a, const Point& b){
    return a.second < b.second;
}

Point my_minus( Point&a, Point& b){
    return Point(a.first,a.second-b.second);
}

class CatchTheBeatEasy{
public:
string  ableToCatchAll(vector<int> x, vector<int> y){
    vector<Point> points;
    for(int i = 0 ; i < x.size(); ++ i)
        points.push_back(make_pair(x[i],y[i]));
    sort(points.begin(),points.end(),my_cmp);
    adjacent_difference(points.begin(),points.end(),points.begin(),my_minus);
    int start = 0;
    for(int i = 0 ; i< points.size(); ++i){
        if(abs(points[i].first-start) > points[i].second) return "Not able to catch";
        start = points[i].first;
    }
    return "Able to catch";
}
};