力扣56.合并区间

• 按左端点排序

  • 判断左端点是否小于等于当前右端点**（可以合并）**

•   class Solution {public:vector<vector<int>> merge(vector<vector<int>>& intervals) {ranges::sort(intervals);vector<vector<int>> res;for(auto &t:intervals){if(!res.empty() && t[0] <= res.back()[1])res.back()[1] = max(res.back()[1],t[1]);elseres.emplace_back(t);}return res;}};