Leetcode 56. Merge Intervals

Given an array of intervals where intervals[i] = [starti, endi], merge all overlapping intervals, and return an array of the non-overlapping intervals that cover all the intervals in the input.

Example 1:

Input: intervals = [[1,3],[2,6],[8,10],[15,18]]
Output: [[1,6],[8,10],[15,18]]
Explanation: Since intervals [1,3] and [2,6] overlap, merge them into [1,6].
class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        sort(begin(intervals), end(intervals));
        vector<vector<int>> merged;
        
        for (auto& e: intervals) {
            if (!merged.size() || merged.back()[1] < e[0]) {
                // no overlap
                merged.push_back(e);
            } else {
                // some overlap
                merged.back()[1] = max(merged.back()[1], e[1]);
            }
        }
        return merged;
    }
};