贪心之区间问题

每日一题ing，今天是个medium题452. Minimum Number of Arrows to Burst Balloons

class Solution {
public:
    static bool cmp(vector& a,vector& b)
     {
        return a[1]>& points) 
    {
        sort(points.begin(),points.end(),cmp);
        int num=0,i=0,flag=0;
        while(i