56. Merge Intervals

https://leetcode.com/problems/merge-intervals/description/

class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& intervals) {
        sort(intervals.begin(), intervals.end());
        
        vector<vector<int>> answer;
        answer.push_back(intervals[0]);

        for (int i=1 ; i< intervals.size() ; i++) {
            if (answer.back()[1] >= intervals[i][0]) {
                if (answer.back()[1] > intervals[i][1]) {
                    continue;
                }
                answer.back()[1] = intervals[i][1];
            }
            else {
                answer.push_back(intervals[i]);
            }
        }

        return answer;
    }
};