合并重叠的区间

这一题不能用差分数组，因为 [1 , 4] [5, 6] 这个就会被合并，正确的做法就是先排序

bool cmp(vector<int> a, vector<int> b) {if (a[0] < b[0]) return 1;if (a[0] == b[0]) return a[1] < b[1];return 0;
}
class Solution {
public:vector<vector<int>> merge(vector<vector<int>>& intervals) {sort(intervals.begin(), intervals.end());int l = intervals[0][0], r = intervals[0][1];vector<vector<int>> ans;for (int i = 1; i < intervals.size(); i++) {int ll = intervals[i][0], rr = intervals[i][1];if (ll > r) {ans.push_back({ l,r });l = ll, r = rr;}else if (ll <= r) {if (rr <= r) {continue;}else if (rr > r) {r = rr;}}}ans.push_back({ l,r });return ans;}
};