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by Sumit Chourasia | Oct 30, 2020 | Category :coding | Tags : algorithm array data-structure leetcode medium

Merge Intervals - Array - Medium - LeetCode

Merge Intervals - Array - Medium - LeetCode

Given a collection of intervals, merge all overlapping intervals.

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.
NOTE: input types have been changed on April 15, 2019. Please reset to default code definition to get new method signature.

 

Constraints:

intervals[i][0] <= intervals[i][1]

public class Solution {
    public int[][] Merge(int[][] intervals) {
        if(intervals.Length==0){
            return intervals;
        }
        Array.Sort(intervals, (a, b) => { return a[0] - b[0]; });
        var res = new List<int[]>();
        int start = intervals[0][0];
        int end = intervals[0][1];
        
        for(int i=1;i<intervals.Length;i++){           
            if(end>=intervals[i][0] && end <= intervals[i][1]){
                end = intervals[i][1];                
            }
            else if(end < intervals[i][0]){
                res.Add(new int[]{start,end});
                start = intervals[i][0];
                end = intervals[i][1];
            }
        }
        
        res.Add(new int[]{start, end});
        
        return res.ToArray();
    }
}

Time Complexity: O(nlogn)

Space Complexity: O(n)

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