贪心之区间问题(1)

每日一题ing，今天是个medium题力扣435. Non-overlapping Intervals

class Solution {
    
public: 
    int eraseOverlapIntervals(vector<vector<int>>& intervals) 
    {
    
        if(intervals.size()==0)
            return 0;
        
        sort(intervals.begin(),intervals.end(),[](vector<int>& a, vector<int>& b)//按照结束时间从小到大排序
        {
    
            return a[1]<b[1];
        });

        int prev=intervals[0][1],sum=0;
        for(int i=1;i<intervals.size();i++)
        {
    
            if(intervals[i][0]<prev)
                sum++;//和前一个区间重叠的区间需要丢弃
            else
            {
    
                prev=intervals[i][1];
            }
        }
        return sum;
    }
};