一、区间问题

 Leetcode 3111.覆盖所有点的最少矩形数目

class Solution {
public: 
    int minRectanglesToCoverPoints(vector<vector<int>>& points, int w) {
        int n = points.size();
        long long res = 0;
        sort(points.begin(), points.end(), [&](const vector<int>& a, const vector<int>& b) -> bool{
            return a[0] < b[0];
        });     // 按照x坐标进行排序
        int st = points[0][0];
        int cur_l = st, cur_r = cur_l + w;  res ++;
        for (int i = 0; i < n; i ++){
            if (points[i][0] <= cur_r)  continue;
            // 否则需要新开一个区间
            cur_r = points[i][0] + w;   res ++;
        }
        return res;
    }
};