56

56. Merge Intervals (Medium)

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] overlaps, merge them into [1,6].

Example 2:

Input: intervals = [[1,4],[4,5]]
Output: [[1,5]]
Explanation: Intervals [1,4] and [4,5] are considered overlapping.

 

Constraints:

• 1 <= intervals.length <= 104
• intervals[i].length == 2
• 0 <= starti <= endi <= 104

Related Topics:
Array, Sort

Similar Questions:

• Insert Interval (Medium)
• Meeting Rooms (Easy)
• Meeting Rooms II (Medium)
• Teemo Attacking (Medium)
• Add Bold Tag in String (Medium)
• Range Module (Hard)
• Employee Free Time (Hard)
• Partition Labels (Medium)
• Interval List Intersections (Medium)

Solution 1.

// OJ: https://leetcode.com/problems/merge-intervals/
// Author: github.com/lzl124631x
// Time: O(NlogN)
// Space: O(1)
class Solution {
public:
    vector<vector<int>> merge(vector<vector<int>>& A) {
        sort(begin(A), end(A));
        vector<vector<int>> ans;
        for (auto &v : A) {
            if (ans.empty() || v[0] > ans.back()[1]) ans.push_back(v);
            else ans.back()[1] = max(ans.back()[1], v[1]);
        }
        return ans;
    }
};